The invention relates to a 
software update method and a 
software update 
system. The method comprises the following steps: a 
client sends upgrading inquiring information to a 
server, and the upgrading inquiring information comprises 
client version information; the 
client receives update information returned by the 
server when the 
server judges that update is needed according to the client version information and server upgrading target version information, and the update information comprises increment update pack information; the client sends download requesting information to the server, and the download requesting information comprises the increment update pack information; and the client receives an increment update pack sent by the server and corresponding to the increment update pack information, and updates according to the increment update pack. The 
system is upgraded through the scheme, does not need to download all complete installation packs from the server, and greatly reduces the downloading data volume in upgrading, therefore, the 
band width occupied in downloading is less, the 
band width is saved, the downloading success rate is improved, and time consumed in upgrading and updating is reduced.