Objective To introduce a simple fixing method for tail vein injection in mice. Methods Twenty tumor-bearing male BALB/c nude mice were used in this study. Tail vein injection was performed to these mice by two laboratory technicians A and B, respectively. The injection time and success rate were recorded and analyzed. Results Mouse tail vein injection was successfully completed by the two technicians with the cage lid pressing method. Conclusions Cage lid pressing method is a simple method for tail vein injection in mice, especially provides a more efficient method for those special form of mice.