TECHNOLOGY FOCUS - BIOTECHNOLOGY - Preferred Method: After the first resting-cell transforming reaction, the removed cells are directly or appropriately processed and added in a second bath of plant sterol transforming liquid to carry out the second resting-cell transforming reaction to transform the plant sterol in the transforming liquid and obtain the androstendione/androstadiene; the bacterial cells are removed; the second transferring liquid is combined with the first transferring liquid through solvent; and the androstendione/androstadiene is obtained by distilling through solvent. The first resting-cell transforming reaction lasts not greater than 45 hours. The technique is to inoculate the microbe stains, used for obtaining androstendione/androstadiene by decomposing plant sterol in cultivating liquid, where the cultivating liquid is separated from the bacterial after culturing; and the bacterial sediment is used as the resting cells. The technique is to inoculate the microbe stains used for obtaining androstendione/androstadiene by decomposing plant sterol in cultivating liquid containing plant sterol to transform, ferment, and culture the plant sterol microbes; the plant sterol is continuously added in the transforming and fermenting cultivating liquid to maintain the concentration of the plant sterol over 0.1%; after the transforming and fermenting culture, the transforming and fermenting cultivating liquid is separated from the bacteria; the obtained transforming and fermenting cultivating liquid is distilled by solvent to obtain androstendione/androstadiene; and the bacterial sediment is used as the resting cells. One liter of the substrate used for the resting cells comprises corn pulp (preferred) or refined honey, inorganic salt and sugar; the inorganic salt is ammonia phosphate and sodium nitrite; the ratio between the ammonia phosphate and the sodium nitrite is 10:40-99; the sugar is glucose; and the resting cells can be washed by phosphoric acid buffer liquid. The plant sterol is crushed or mixed with solvent and slowly mixed with the transforming liquid to contact the resting cells. The resting cells of the microbe strains are directly or appropriately added in the plant sterol transforming liquid; the direct use of the resting cells refers to directly centrifuge the cultivating liquid or filtering to obtain the bacterial sediment after cultivating the microbes; the appropriate treatment comprises heating the bacterial sediment at 40-90 degrees C for a certain time to obtain the dead bacteria; or the bacterial sediment is treated by any one known fixing method to obtain the fixed bacteria; or the bacterial sediment releases enzyme in the solution by self-dissolving or crushing cells, removing crushed cells by centrifuging or filtering; and the obtained enzyme distilling liquid of the cells is purified by the ammonia sulfate separating method, the ion switching layer separating method and the gel filtering layer separating method to obtain the enzyme agent. The microbe strains used for obtaining androstendione/androstadiene is Mycobacterium strain NRRL B-3683, NRRL B-3805, or NRRL B-8135.