A routing method of a wireless sensor and actuator network for fire protection comprises the steps that the number of actuator nodes and positions of sensor nodes are determined; a wireless fire extinguishing system network is divided into a plurality of clusters by using a weighed Voronoi diagram method; according to topological information of each cluster, a routing path is calculated by using a degree-constrained minimum spanning tree; each cluster is composed of one actuator node and a group of sensor nodes, and the actuator nodes switch residual energy information with each other and send a routing table and received energy information to each sensor node in each respective cluster; and each sensor node inside a cluster transmits residual energy information to the actuator node according to the received routing table. According to the routing method, degree-constrained minimum spanning tree algorithm is used for calculating routing paths between the actuator nodes and the sensor nodes in the fire extinguishing system network, network energy consumption is reduced, and fairness of energy consumption of network nodes is also promoted at the same time.