Abstract: A building HVAC control system is provided, including at least one wireless mesh network. The wireless mesh network includes a plurality of wireless mesh nodes, the wireless mesh nodes include: at least one sensing node, configured to communicate with sensors installed in a building and obtain measured environment data collected by the sensors; at least one control node, configured to communicate with HVAC equipment, and send control commands to the HVAC equipment; at least one router node, configured to transmit data between the wireless mesh nodes, and transmit data between the wireless mesh nodes and the router. The wireless mesh nodes can perform device-to-device communications by transmitting and receiving wireless signals through the mesh without passing through the server, thereby enabling efficient, multi-node control loops that add no additional computational load to the server while increasing the safety of data transmission and the overall reliability of the HVAC control system.