1. A method for testing server with mixed workloads, where multiple clients serving as agents and controlling device are connected with a server under test via a network, characterized in that: comprising steps of the third party develops one or more workload case configure utilities corresponding to one or more workload cases, each of said utilities implements a workload case configure utility interface; the third party develops one or more workload engines corresponding to one or more workload case, each of said engines implements a workload interface; said controlling device configures workload cases by calling corresponding ones of said workload case configure utilities through said workload case configure utility interface, and transfers the information collected during the configure process to corresponding agents; each of said agents controls corresponding workload engine through said workload interface to generate workload requests by using the information collected during the configure process, and sends said requests to the server; said controlling device collects response information from all the agents, and generates test results.