Winding temperature rise is a key performance index in the design and operation of surface-mounted permanent magnet synchronous motor (SPMSM), and its accurate calculation is crucial to the safety and reliability of the motor. To address this issue, this paper proposes an analytical modeling method for the 3D transient thermal network of SPMSM based on a single pole and single slot. Firstly, the winding in slot is equivalently treated and converted into a conductor with variable thermal conductivity. Key structural parameters such as wire diameter and stator slot size are comprehensively considered, and comparative verification is carried out through finite element simulation. Secondly, on the basis of 2D equivalent model of the winding in the slot, an analytical model of 3D transient thermal network for the single pole and single slot is constructed. The heat transfer path between stator and the winding in slot is simulated through tile body network topology, so as to realize the temperature solution of each node. Finally, taking a 20-poles 24-slots SPMSM as the research object, a winding temperature rise test platform is built. The accuracy of the proposed model is verified by comparing and analyzing experimental data with calculation results of the thermal network model.