Abstract: To probe into the motion laws of Oncomelania in channel flows,the paper investigates the threshol d velocity of Onco melania st icking to the boundary of channel by means of experimentals in flume; two formule for the threshold velocity are derived based on the theories of river mechanics and biomechanics and the elements which effect on the threshold velocity have been analyzed.The results show that,because of the eminent biological adsorptive power,the treshold velocities for Oncomelania with open operculum and sticking to the boundary of channel are statistically much great than that for Oncomelania with close operculum and justlying on the channel bed,however,the theshold velocities scatter whthin wide limitas.