To evaluate the effect of biological controlling of Alitropus typus ,the seasonal variation of Alitropus typus population were monitored via two methods,the trapping way and gill net,in Hejiang River from 2006 to 2010.The results of the seasonal population dynamics indicated that the parasitic number of A.typus was the least from April to June,the life cycle of A.typus was presumed to be one year and the alternation of generations occurred in June annually.However the overlapping between generatations was not significant.In addition,the experimental results showed that Ctenopharyngodon idellus , Mylopharyngodon piceus , Cyprinus carpio were able to prey A.typus, which suggested that these fishes could be potential factors that could biologically cotroll A.typus. For the lowest parasite rate of A.typus appeared from April to June,this period was selected to release C.idellus , M.piceus and C.carpio into Hejiang River each year from 2007 to 2009.A total 1.56 million fish were released into Hejiang River during three years.While the number of A.typus captured by the trapping way gradually decreased since 2008.The number of A.typus in 2010 decreased 85.1% than that in 2006. Cirrhinus molitorella and Hemiculter leucisculus were sampled by gill net placed at the same location from September 2006 to August 2007 and from September 2009 to August 2010.The results indicated that prevalence,mean infection intensity and mean density of A.typus were dramaticallydecreased from September 2009 to August 2010.All the results showed that biological control measures were effective in Hejiang River.