The invention provides a missile weapon system basic level maintenance modeling method based on Petri network. The missile weapon system basic level maintenance modeling method based on the Petri network comprises the following steps that Step 1, according to the actual utilization of a missile weapon system and the workflow of the basic level maintenance, the basic level maintenance work is divided into maintenance events, maintenance actions and maintenance operations according to hierarchy, each maintenance operation is analyzed in a logical relation and a temporal relation, the logical relation comprises a definitive type relation and a probabilistic type relation; Step 2, based on a logic sequence and a time sequence among the maintenance operations, modeling is conducted by using the Petri network; Step 3, a model A which is built in the maintenance actions of the missile weapon system basic level maintenance work by using the Petri network is simplified. By the modeling of the maintenance actions of the definitive type adjacency relation and the probabilistic type adjacency relation, the required maintenance action time data are acquired and maintenance resource quantity is confirmed, and the missile weapon system basic level maintenance support work can be assured of going smoothly.