NOVELTY - Preparing celastrol derivative involves storing potato at 4 degrees C and then placed potato in an inclined culture medium of a culture box at 25 degrees C for 7 days. Sterile water is flowed into the inclined surface of spore, where single spore suspension concentration is adjusted to 107-108 months/ml to obtain spore seed solution. The spore seed solution (100 ml) is inoculated in potato liquid culture (5 ml) at pH 6.0 having temperature 30 plus minus 1 degrees C with oscillating speed of 200 revolutions per minute for 12 hours.    USE - Method for preparing celastrol derivative used for treating tumor associated diseases such as liver cancer, prostate cancer, ovarian cancer, adenocarcinoma, breast cancer, leukemia, colon cancer, adriamycin sensitive lung cancer, breast cancer, liver cancer, lung cancer, breast cancer, liver cancer and adriamycin drug-resistant tumor system, for virus related diseases such as AIDS, hepatitis B, herpes, influenza, for nerve impairment correlations of diseases such as Alzheimer's disease, Parkinson's disease, Huntington's disease and spinal cord injuries and amyotrophic lateral sclerosis (all claimed).    ADVANTAGE - The method enables to provide high yield of celastrol derivative in an eco-friendly manner. The celastrol derivative has high selectivity and low toxicity.    DETAILED DESCRIPTION - Preparing celastrol derivative involves storing potato at 4 degrees C and then placed potato in an inclined culture medium of a culture box at 25 degrees C for 7 days. Sterile water is flowed into the inclined surface of spore, where single spore suspension concentration is adjusted to 107-108 months/ml to obtain spore seed solution. The spore seed solution (100 ml) is inoculated in potato liquid culture (5 ml) at pH 6.0 having temperature 30 plus minus 1 degrees C with oscillating speed of 200 revolutions per minute for 12 hours. Different proportions of combined elicitor are added and continuously cultured for 12 hours, and then celastrol is mixed to obtain mixture. The mixture is cultured for 5 days and conversion content of celastrol derivative is detected each day, when product conversion rate is 0.5-3% then culturing is stopped. The mixture is filtered and collected where filtrate is centrifuged at speed of 8000 revolutions per minute for 10 minutes to obtain precipitate. Precipitate is removed to obtain fermenting extraction liquid. Extraction liquid is extracted thrice by using same volume of ethyl acetate to obtain extracts. The extracts are mixed with ethyl acetate in weight ratio 1-3 to 1-10 by using ultrasonic extraction for 30 minutes and then filter body is removed and separated to obtain extraction liquid. The extraction liquid is concentrated and dried to obtain residue. The residue is dissolved by using acetone (1-10ml), silicon glue (20 times) and petroleum ether (100%) with low polarity order. The sample is eluted by using petroleum ether and methylene dichloride in volume ratio 5:2, 2:3, 2:5 and 0:5, and dichloromethane and ethyl acetate in volume ratio 10:0, 8:1, 6:1, 4:1, 2:1, 1:1, 1:2, 1:4, 1:6 and 1:8. Sample is collected over a thin-layer chromatography and a rotary evaporator with help of pure methanol. Sample is filtered through an organic film (0.22 microns) to obtain solution. The solution is separated and purified by using a high efficient liquid phase HPLC gradient elution method for collecting different celastrol derivative eluents. Different celastrol derivative eluents are decompressed, where solvent is evaporated to obtain celastrol derivative. 3-Hydroxy-celastrol derivative of formula (I) and 2,3-hydroxy-celastrol derivative of formula (II).    R1=hydrogen, alkyl, acid radical or organic acid radical substituted 10C-alkoxy, 10C-hydroxyl substituted alkyl, where acyl is nitrogen-containing heterocyclic ring or oxygen-containing heterocyclic ring, organic acid radical is fatty acid or aromatic acid, fatty acid is acetate, propionate, butyrate, sulfoacid radical, acetone, cinnamoate, succinate, citrate, lactate, glucose, lipoic acid, N-acetyl cysteine or amino acid and aromatic radical is benzoate or pyrazine acid radical;    X1 and X2=hydroxyl or hydrogen;    R1'=hydrogen or alkyl substituted by 2C-alkoxy or 2C-hydroxyl substituted alkyl; and    X1' and X2'=hydroxyl, hydrogen, acyl or organic acid radical acyl, nitrogen-containing heterocyclic ring or oxygen-containing heterocyclic ring, where organic acid radical is fatty acid or aromatic acid, fatty acid is acetate, propionate, butyrate, sulfoacid radical, acetone, cinnamoate, succinate, citrate, lactate, glucose, lipoic acid, N-acetyl cysteine or amino acid and aromatic radical is benzoate or pyrazine radical,    provided that:    (A) when R1 is hydroxymethyl, then X1 and X2 are hydroxyl or hydrogen;    (B) when R1 is carboxyl, then X1 and X2 both are hydroxy or hydrogen;    (C) when R1' is hydrogen, then X1' and X2' is hydroxyl or hydrogen or both hydrogen; and    (D) when R1' is hydroxide radical, then X1' and X2' hydrogen.