NOVELTY - Synthesizing polythiophene-fullerene-polylactic acid triblock copolymer, comprises: (i) adding substituent polythiophene and anhydrous toluene in a reaction bottle, introducing nitrogen, magnetically stirring, heating, injecting N-methyl carbonylaniline and phosphorus oxychloride, cooling, vacuum drying; (ii) adding aldehyde group modified polythiophene, sarcosine, fullerene and toluene, magnetically stirring; and (iii) adding fullerene sealed polythiophene, para hydroxy benzaldehyde, sarcosine and toluene, introducing nitrogen, stirring and reacting, depositing using methanol, centrifuging.    USE - The method is useful for synthesizing polythiophene-fullerene-polylactic acid triblock copolymer.    ADVANTAGE - The method: is simple and cost efficient; provides high product quality, high input-output ratio; and produces the product, which is environmental-friendly, and is high-performance chemical product, thus the product can be used in the fields of the conductive material, solar cell material, photoelectric material and photoelectric conversion material.    DETAILED DESCRIPTION - Synthesizing polythiophene-fullerene-polylactic acid triblock copolymer, comprises: (i) adding substituent polythiophene (100-1000 mg) and anhydrous toluene (5-50 ml) in a reaction bottle, introducing the nitrogen for protection, magnetically stirring, slowly heating up to 60-120 degrees C until the substituent polythiophene is completely dissolved, injecting N-methyl carbonylaniline (0.1-5.0 ml) and phosphorus oxychloride (0.1-2 ml), stirring and reacting under the nitrogen protection at 50-90 degrees C for 4-36 hours, cooling to 25 degrees C, dropping saturated sodium acetate solution (1-20 ml), continuously stirring and reacting for 0.5-5 hours; pouring the reaction liquid into a liquid separating funnel, allowing to stand and layering, removing the upper-layer oil phase, depositing and separating by anhydrous ethanol (50-250 ml), vacuum drying the product at 30-80 degrees C for 6-48 hours to obtain the aldehyde group modified polythiophene, where the yield is 70-95%; (ii) adding aldehyde group modified polythiophene (10-100 mg) in the step (i), sarcosine (10-100 ml), fullerene (10-100 mg) and toluene (5-50 ml) into the reaction bottle, introducing the nitrogen for protection, magnetically stirring, slowly heating up to 30-90 degrees C until the substituent polythiophene is completely dissolved, heating up to 50-150 degrees C, stirring and reacting for 6-48 hours to obtain the fullerene sealed polythiophene, where the number average molecular weight is 5000-15000, and the yield is 80-96%; and (iii) adding fullerene sealed polythiophene (10-100 mg) obtained in the step (ii), para hydroxy benzaldehyde (5-50 mg), sarcosine (15-100 mg) and toluene (5 to 100 ml) into the reaction bottle, introducing the nitrogen for protection, stirring and reacting at 60-150 degrees C for 6-96 hours, depositing it by methanol (10-80 ml), centrifuging and separating at 1000-8000 revolutions per minute, vacuum drying the product at 30-80 degrees C for 6-48 hours to obtain hydroxy-containing fullerene sealed polythiophene (25-200 mg), weighing hydroxy-containing fullerene sealed polythiophene (10-100 mg), D, L-lactide (10-150 mg), stannous octoate (1-15 mg) and toluene (5-50 ml) in the reaction bottle, introducing the nitrogen for protection, stirring and reacting at 50-150 degrees C for 6-96 hours, cooling it to 25 degrees C, depositing and separating by methanol (10-100 ml), vacuum drying the product at 30-80 degrees C for 6-48 hours to obtain the polythiophene-fullerene-polylactic acid triblock copolymer, where the yield is 40-70%.