In order to study bladder intravesical instillation methods in pure line LEW rats and nude mice, female LEW rats and nude mice aged 2 to 4 weeks were sacrificed. Their urethra and bladder were observed under anatomical microscopy. A trochar was prepared according to the outline and an- gle of the urethra. Ink was poured into female rats and nude mice bladder though urethra. Filling and staining of bladder were observed and evaluated under anatomical microscopy. Status and urethral injury of rats and mice were observed. The results showed that urethra anatomic structure of rats and nude mice was different from that of human urethra. When bladder was filled with ink and became blue, liquid was not seen to leak out. The success rate of intubation was high (100%). Living activi- ties of animals weren’t influenced by intravesical instillation. It was concluded that bladder irrigation might be a kind of valid and utilizable method in pure line rat and nude mouse empirical study. The model may be a more effective tool for study of bladder tumor.