Abstract: Lectin，saponins，phytic acid and trypsin inhibitor are main anti- nutritional factors in common beans. Dynamic changes of these anti-nutritional factors were studied by determining their levels in dwarf and trail common bean pods on 6 growth periods. The results showed that levels of lectin and trypsin inhibitors increased during the whole growth periods in both common bean varieties，reached the peak at 21-28 days. For lectin from 0. 35 mg/g to 0. 92 mg/g and from 0. 36 mg/g to 0. 54 mg/g，and for trypsin inhibitor from 0. 18 TIU/g to 5. 02 TIU/g and from 0. 50 TIU/g to 4. 68 TIU/g，in dwarf and trail common beans respectively. Levels of saponins and phytic acid showed a general downward trend，with the former decreased from 55. 21 mg/g to 18. 90 mg/g in dwarf common beans and from 43. 33 mg/g to 11. 79 mg/g in trail ones，and the latter from 15. 07 mg/g to 14. 33 mg/g in dwarf common beans and from 14. 57 mg/g to 12. 19 mg/g in trail ones. 14-21 days after blossom，both common beans were of appropriate ripeness and contained relatively lower anti-nutritional factors，and were fit for harvest. 28 days after blossom，both common beans were fully ripened with high levels of anti-nutritional factors，and needed thorough cooking before served.

Key words: commom bean, anti-nutritional factors, lectin, saponins, trypsin inhibitor, phytic acid