TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Method: The step (a) comprises drying cotton seed meal to a constant weight, adding into a grinding machine, sieving through 80-mesh sieve to obtain milled powder, stirring the powder in an expansion solvent, pressurizing to 3-8 MPa, stirring at 0-80 degrees C, preferably 20-30 degrees C for 1-4 hours, reducing the pressure to atmospheric pressure, filtering insoluble substances, transferring the insoluble substances in the expansion solvent of acetone, carrying out extraction in an ultrasonic-microwave synergistic extractor for two times at a ultrasonic power of 40-60 W and microwave power of 120-250 W for 30-90 minutes, combining the two extracted solutions, concentrating to a volume of 1/3, adding 10-90%, preferably 20-50% aqueous acid solution (formic acid or acetic acid), preferably acetic acid, continuously stirring, separating out solid, centrifuging and separating to obtain racemic gossypol compound, where the expansion solvent comprises 10-20% acetone and 90-80% carbon dioxide, the ratio of expansion solvent and milled powder is 1.2-2.5 ml/g and the mass ratio of the milled powder and acid aqueous solution is 1-10:1, preferably 2-8:1. The step (b) comprises mixing n-butyl alcohol, ethyl acetate and water in a volume ratio of 1-1.6:3-5:1, mixing well, allowing to stand to stratify, where the upper layer is taken as a stationary phase and the lower phase is taken as a mobile phase, ultrasonically degassing the two phases for 20-40 minutes. The step (c) comprises firstly pumping the stationary phase into the high speed counter-current chromatography column, starting the main machine at a rotating speed, pumping the mobile phase into the chromatographic column, allowing to reach two-phase dynamic equilibrium, dissolving 150 mg racemic gossypol compound crude product dissolved in 4-7 ml stationary phase and 4-7 ml mobile phase to obtain sample solution, feeding the sample solution through a sample inlet, continuously pumping the mobile phase, carrying out reverse phase HPLC, determining the peak position of L-gossypol compound, collecting the separated fraction, desolventizing to obtain L-gossypol compound, where the rotation speed is 500-1000 revolutions per minute, preferably 650-850 revolutions per minute and the flow rate of the mobile phase is 5 ml/minute, preferably 1-3 ml/minute. The reverse phase HPLC column is 150 mmx 4.6 mm, 5 mu m Chiralcel OD-RH (RTM: Chiral stationary phase (Cellulose tris(3,5-dimethylphenylcarbamate)) coated on silica-gel) column, where the column temperature is 30 degrees C, the mobile phase is triethylamine phosphate buffer solution of pH 3.5 and acetonitrile in a volume ratio of 30:70, the flow rate is 1 ml/minute, the UV detection wavelength is 225 nm and the sample size is 10 mu l. The step (d) comprises dissolving L-gossypol compound in ether, adding 0.1% sodium bisulfite solution, stirring, washing ethyl ether phase with water for twice, drying by anhydrous sodium sulfate, filtering, vacuum extracting and distilling ethyl ether, again extracting with ethyl ether, washing to remove ether, re-crystallizing by petroleum ether to obtain L-gossypol, where the volume ratio of ethyl ether, sodium bisulfite and gossypol compound is 12 ml: 24-36 ml: 1 g. Preferred Components: The amount of expansion solvent based on the amount of milled powder is 1.5-1.8 ml/g.