Objective To establish an improved method for chromosome aberration testing in mouse spermatogonia, obtain large amounts of constant and clear metaphase chromosomes for reading, and apply the improved method to assess the mutagenic effect of Maca. Methods Thirty male ICR mice were randomly divided into six groups with five mice in each group. Seminiferous tubules were minced for spermatogonial cell enrichment. The fragments were treated with a 1. 5 mg/ mL collagenase solution (in serum-free culture medium at 35℃ for 15 minutes with intermittent agitation (3 minute intervals). After routine hypotonic treatment, fixation, and cell smearing, slides were observed under a microscope and compared with those prepared by the conventional method. Results A large number of well-dispersed metaphase phase spermatogonium with a clear background and compact chromosome structure were prepared and observed by our method, and the chromosome slides prepared by this method were easy to read. Compared with the result with the conventional method, the number of high magnification fields required for observation was significantly decreased (P<0. 01) and the mitotic index was obviously increased ( P< 0. 01 ). The chromosomal aberration rate of the cyclophosphamide-positive control group was significantly higher than that of the control group (P<0. 01). No significant differences were found in the chromosome aberration rate between the Maca groups of various dosages and the control group(P>0. 05). Conclusions The enrichment efficiency of spermatogonial cells and the success rate of experiments were improved by the modified method, and this method was significantly better than conventional method. Maca had no effect on the chromosomes of mouse spermatogonial cells under the experimental conditions.