M3 strain with deletion of ul7, ul41 and LAT genes of herpes simplex virus 1 type (HSV-1) was constructed by CRISPR/Cas9 system. M4 strain was obtained by deletion of us3 on the basis of M3 mutant. The purpose of this study was to analyze the differences between McKrae, M3 and M4 strains in attenuation and anti-apoptosis. The results showed that there were obvious clinical symptoms in McKrae group, and 100% of the mice died (P<0.001). No clinical symptoms were found in M3 and M4 groups. The viral load in M4 group was significantly lower than that in McKrae and M3 groups. Pathological examination showed that there were some phenomena such as arachnoid hemorrhage and glial nodules in McKrae group, but no pathological damage was found in M3 and M4 groups. The expression of inflammatory factors in M4 group was significantly lower than that in McKrae and M3 groups (P<0.01). High levels of neutralizing antibodies, interferon γ (IFN-γ) and interleukin 4 (IL-4) antigen-specific T cells were observed in M4 group compared with M3 group after immunization. M4 group had lower viral load than the control and M3 groups when McKrae was re-infected. In Jurkat cells, M4 strains could significantly induce apoptosis compared with McKrae and M3 strains.