【Abstract】 Objective To study activity variance of carboxylesterase，glutathione S?transferase and acetylcholinesterase in different development stages and gender adults of German cockroach (Blattella germanica). Methods Enzyme activities were measured by spectrophotometry in vitro and the data were analyzed with software DPS. Results The activities of carboxylesterase and acetylcholinesterase in the first?instar nymphae were the highest and the activities values were （0.3741±0.0077）μmol/（mg pro·min） and  （61.7586±9.2400）nmol/（mg pro·min）, respectively. The differences among different development instars were significant. The activity of carboxylesterase in male adults was higher than that in female adults, and the difference between them was significant. For acetylcholinesterase, the activity in male adults was higher than that in female adults, but the difference was not significant.  The  activity  of  glutathione  S?transferase  among  different  development  stages  and  gender  adults  had  almost  no difference. Conclusion The activity differences of carboxylesterase and acetylcholinesterase among different development stages and male, female adults were significant whereas that  of glutathione S?transferase was not significant.