For a long time past viruses have been recognized as being tumoricidal. At present, researchers are still pursuing studies and constructing more suitable oncolytic viruses for treating different malignant tumors. Herpes simplex virus type 1 (HSV-1) has been known as the most potential oncolytic virus among all the viruses. In this overview, we summarize the current situation of oncolytic viruses, the biology of HSV-1, its construction and application of its recombinant, and we debate on the feasibility and prospect of HSV-1 mutants labeled with radionuclides for cancer therapy.