Abstract: With the rapid development of satellite technology,satellite applications are more and more complicated.The applicability of using Hierarchical Task Network (HTN) to do complex satellite application task decomposition was studied and the relevant working frame was given.The main contents and steps of the pretreatment of the satellite application task requirements were put forward,and the domain model of satellite application tasks was constructed.Finally the definitions of complicated tasks and it′s decomposing method were presented and HTN was used to calculate the complex satellite application mission decomposition and an estate space forward searching arithmetic based on HTN was presented.