Abstract: Due to the loose bolts at the connection of the wire clamp, the poor contact condition of the contact surface and the deterioration of the environmental conditions, the temperature of the wire clamp is every high, which affects the normal operation of the transmission line. The previous researches ignore the actual environment and the surrounding flow field of the wire clamp, which makes it impossible to get its internal temperature in real time accurately. According to the theory of hydrodynamics and heat transfer, the three-dimensional finite element models of NY300/40 tension clamp and LGJ300/40 steel core aluminum strand are established, and their steady-state thermal analysis is carried out by using ANSYS Workbench platform. The results reveal changes of temperature field in overhead transmission line clamps under different current, different bolt torque and different environmental conditions. Finally, the accuracy of the numerical calculation is verified by the thermal stability monitoring system of power transmission and transformation equipment, and the maximum error is less than 6%. The research results can provide technical supports for the temperature monitoring system of power transmission and transformation equipment.