Abstract: The processing factors (PF) of 4 pesticides (trichlorphon, chlorpyrifos, cypermethrin, carbendazim) in Brasenia schreberi Gmel were investigated in order to improve the processing treatment. The washing, blanching, green-protecting, and storage processing were simulated and the effects of each processing on PF of the above 4 pesticides were studied. The residues of trichlorphon and chlorpyrifos were detected with GC-FPD. And the residues of cypermethrin and carbendazim were determined by GC-ECD and LC-DAD, respectively. The results showed that PF of 4 pesticides reduced gradually with the increasing of washing time. However, it reached to a stable state after a certain time. Within the range of 10 minutes, the PF of 4 pesticides kept reducing with the increasing of blanching time. There were no significant effects of green-protecting and storage processing on the PF of 4 pesticides. Given the quality and pesticide residues of B. schreberi, about 30 minutes' washing time was recommended, and the blanching time should be extended as long as the quality is not influenced.