OBJECTIVE To propose a simple and practical method for preparing a mouse model of oligo-astheno-terato-spermia/azoospermia, and to offer a methodological suggestion for the studies on the related mechanism of spermatogenesis and evaluation of medication efficacy by observing the early changes of testis morphology after 5-fluorouracil treatment. METHODS Mice were injected with a single dose of 5-flourouracil at 250 mg/kg via the tail vein, and their testes were harvested and paraffin sections prepared before and 3, 7, 11 and 14 d after the injection to be observed for the morphological changes by hematoxylin and eosin staining. RESULTS The numbers of spermatocytes/spermatids were progressively reduced inside the testis seminiferous tubules of the mice at 3, 7 and 11 d after the 5-fluorouracil injection, and the tubule walls became thinner, which reached the nadir at 11 d, with evident swelling and crazing of the seminiferous tubules. At 14 d, the swelling almost disappeared and spermatocytes became repopulated, while the flaws still existed in the seminiferous tubules and no mature sperm were seen. CONCLUSIONS One-dose injection of 5-fluorouracil via the tail vein might be a simple and effective method for preparing the animal model of reproductive function damage induced by chemotherapeutic medication.