The present invention discloses a proxy gateway anti-virus method, a pre-classifier, and a proxy gateway. The method includes: receiving a resource obtaining request for obtaining a to-be-transmitted resource; sending a pre-detection request to a network element that stores the to-be-transmitted resource, to obtain attribute information of the to-be-transmitted resource; judging, based on an anti-virus policy and according to the attribute information, whether the to-be-transmitted resource needs anti-virus scanning; if yes, performing anti-virus scanning on the to-be-transmitted resource that is subsequently obtained; and if no, transparently transmitting the to-be-transmitted resource that is subsequently obtained. The present invention provides a technical solution to pre-detecting whether a to-be-transmitted resource needs anti-virus scanning according to attribute information, and a resource that needs no anti-virus scanning can be transmitted transparently and directly before the resource is sent to a proxy layer, thereby implementing an anti-virus function, improving transmission efficiency, and reducing the waste of resources.