A large quantity of mice McAb ascites with monoclonal antibody (McAb) hybridoma cells separated from mice ascites was prepared. Ascites of mice inoculated with McAb hybridoma cells were collected, and the McAb hybridoma cells were isolated by centrifugation with lymphocyte separating fluid. McAb hybridoma cells then were injected into other mice abdominal cavity to prepare ascites again. McAb hybridoma cells separated from a mouse could be injected into the abdominal cavity of 5 mice.　Each mouse could produce 3.97 ml ascites on average. This method could be used to prepare large quantity of high titer mice monoclonal anti-HBs/a ascites.