Cloud computing technology is an efficient way to resolve the resource sharing and cooperative work in distributed environments. The resource discovery mechanism is a key problem in Cloud computing. In order to implement the quick discovery of service resource and the balanced distribution of resource on the Cloud computing system, a resource discovery mechanism in Cloud computing environment has been designed and implemented. Firstly, a Formula based on each node's loading has been proposed. Secondly, a comprehensive service distribution method has been designed in consideration about each node’s performance and current loading distribution. Finally, the result of the experiment indicates that the discovery mechanism can improve the efficiency of the resource and the utilization ratio of the service resource.