Abstract: In the paper, the research started from the cloud computing resources that needed by the user's computing tasks. Firstly, the paper proposed the cloud computing resources combination and billing patterns based on user task, and then modeled by Petri net. At last, the analysis of an application example shows that the system can output the list of all the resources combination and billing patterns after submitted the user task, thereby help the user for decision analysis when the user ordered the cloud computing resources.