Abstract: The research on the energy conversion process, distribution and flow characteristics in the inductively coupled plasma(ICP) heater is helpful to provide theoretical guidance for the design of ICP heater and support its development with high-power, multi working gas and more applications. In this paper, the coupling calculation of magnetic field, fluid heat transfer and laminar flow field of argon cylindrical ICP torch was carried out by using COMSOL based on the assumptions of two-dimensional axisymmetric geometry, laminar flow and local thermodynamic equilibrium in the heater. The temperature field, energy distribution and flow field in the heater were obtained. The process of energy conversion, heat transfer and gas flow were analyzed. At the same time, the rationality of the numerical simulation was verified by comparing with the temperature measured by spectrum method. The results show that the highest temperature zone in the torch is symmetrically distributed in the area covered by the coil and there is a certain distance from the outer quartz tube, which is caused by skin effect. The temperature in the center of this area is slightly lower. At the outlet of the heater, the temperature is high and uniform in a certain range of the center and decreases to both sides. The high velocity zone of gas flow is located in the center of the torch corresponding to the bottom coil and its downstream region. A recirculation zone is generated in the upper part of the plasma torch.