Objective In this study，2-butyloxide-5-butylaminobenzoic acid（BBA）was synthesized with butyric acid and 5- aminosalicylic acid，which can be used as the prodrug for the treatment of colon cancer. The sustained-release preparation of BBA nanocrystals expected with good targeting and high bioavailability was prepared by using nanotechnology，which could effectively solve the problems of antitumor drug solubility and pharmaceutical properties. Methods BBA nanocrystals were prepared by solvent-antisolvent precipitation，and were characterized by NMR scanning，infrared spectrometer and transmission electron microscopy. High-performance liquid chromatography（HPLC）was used to detect the content of BBA. The cell viability of SW620 cells treated with different concentrations of BBA，BBA nanocrystals，blank nanocrystals，5-fluorouracil（5-FU），5-aminosalicylic acid（5-ASA）and sodium butyrate （NaB）were detected by MTT assay. Results BBA nanocrystals were successfully prepared. MTT results showed that the in vitro inhibitory effect of BBA nanocrystals on colon cancer cells of SW620 was slightly lower than that of the positive control group of 5-FU（P > 0.05），but was similar to the other groups at the same concentration，indicating that BBA nanocrystals showed desire inhibitory effect on colon cancer cells SW620 in vitro（P < 0.05）. Conclusion In the present study，we successfully prepared the nanocrystals of BBA as the pro-drug of butyric，which proved that the new drug preparation showed an inhibitory effect on colon cancer cells，and might provide an extremely significant new idea and original approach for the clinical treatment of colon cancer.