The present invention provides an oncolytic virus formulation and preparation method thereof. The oncolytic virus formulation comprises cell vesicles derived from apoptotic tumor cells and oncolytic viruses coated in the cell vesicles as an effective component. The oncolytic virus formulation uses cell vesicles derived from tumor cells themselves to coat the oncolytic viruses, so as to evade the body's immune system attack and can be targeted to the tumor treatment site, and improve the tumor-killing effect.