Objective The breeding and identification method of Bmal1 knockout mice were analyzed to provide an ideal animal model to study various biological rhythms. Methods Bmal1 knockout mice were fed and bred in cages of one male and two females. Tail genomic DNA of the mice was extracted from the offspring, the target gene fragment was amplified by PCR, and the PCR product was analyzed by gel electrophoresis. Bmal1 protein expression in myocardial tissue was detected by Western Bolt to verify the Results. Results Compared with those of Bmal^{+ / +} mice, the phenotypes of Bmal^{- / -} mice showed no significant difference except for body weight, and homozygous knockout mice lost their reproductive ability. Changes in 24 h blood glucose rhythm of Bmal^{- / -} mice. Bmal1 knockout mice were successfully bred, and a batch of knockout mice was obtained. Conclusions PCR identified homozygous mice with Bmal1 gene knockout. PCR amplification was an effective method to detect the mouse gene.