polysaccharide peptide (GLPP) has multiple pharmacological activities. The purpose of this study was to determine whether GLPP could protect the male sperm production from chemotherapeutic injury using a mouse model, with testicular damage induced by cyclophosphamide (CP). CP (50 mg/kg/day) was injected intraperitoneally into male ICR mice gavaged with different doses of GLPP at certain spermatogenic stages. The experimental results showed that GLPP alleviated the CP-induced reduction in reproductive organ coefficients and sperm parameters and reduced the morphological damage of testicular tissues in a dose-dependent manner. GLPP significantly improved the reproductive index, sperm-related parameters, sex hormone levels, and histological testis architecture at different spermatogenic stages. Furthermore, GLPP significantly increased superoxide dismutase (SOD), glutathione (GSH), catalase (CAT), Nrf2, and HO-1, and decreased malondialdehyde (MDA) and Keap-1 in the testicular tissue, indicating reduced oxidative stress. In addition, GLPP limited CP-induced apoptosis via a reduction in Bax expression and increase in Bcl-2 expression. This study suggests that GLPP plays a protective role in spermatogenesis by reducing chemotherapeutic injury and might be developed into drug for male patients receiving chemotherapy.