This invention belongs to the field of biomedicine and relates to use of Bcl-xL inhibitor and oncolytic virus in the preparation of an anti-tumor drug. The present invention firstly discovers that the Bcl-xL inhibitor can be used as an anti-tumor synergist for oncolytic virus. The present invention also relates to a pharmaceutical composition comprising Bcl-xL inhibitor and oncolytic virus, a pharmaceutical kit comprising Bcl-xL inhibitor and oncolytic virus, and use of Bcl-xL inhibitor and oncolytic virus for treating tumors, especially, tumors that are not sensitive to the oncolytic virus.