Embodiments of the present disclosure provide a method and a system for upgrading software. The method includes: a client reports a software upgrade request to a server, wherein the upgrade request carries file information of the local software to be upgraded; the server determines the difference with the latest version software according to the file information of the software to be upgraded in the upgrade request, and generates upgrade instruction information according to the difference and sends it to the client; the client downloads and updates the relevant files and performs the relevant local upgrade operations according to the instructions in received upgrade instruction information. Technical solutions of the present disclosure can save bandwidth resources and reduce the workload for upgrading software.