First of all, online computing software service scene is analyzed and hierarchical structure is designed in order to improve service capabilities of the software under dispatching and control cloud. And in "skinny client, fat server" running and operation environment which is similar to browse/server mode, online computing processes are decomposed and encapsulated into computing service units. At the same time, online computation service framework is designed using multi-agent mechanism, and these units will be called and integrated in building blocks way to provide online computing software service. Finally, the dispatcher load flow software service is designed and implemented based on the JADE (Java Agent Development Framework) multi-agent framework, and related performance test and analysis are carried out in detail. The problem that in the meanwhile providing load flow software service will bring low efficiency is analyzed, and further optimization steps are proposed. This work is supported by Science and Technology Project of the Headquarter of State Grid Corporation of China (No. DZB17201800023).