As an important compound semiconductor, Indium phosphide (InP) is extensively utilized in the fields like communication, aerospace and artificial intelligence. The quality of InP single crystal growth depends on the stability and temperature control of the thermal field inside the growth furnace. As a widely used method in the industrial production of InP crystals, the vertical gradient freeze (VGF) method is used to construct a high-temperature, closed, stable and controllable thermal field in indium phosphide single crystal growth furnace. Due to the lack of direct observation and complete parameter monitoring methods in the furnace, the temperature field of crystal growth in the furnace is scientifically analyzed using computer numerical simulation to obtain the best growth temperature control conditions, which has become an effective and important method. This article establishes a three-dimensional physical and mathematical model of the thermal field of InP single crystal growth system based on ANSYS finite element software and measured parameters of furnace components. Based on temperature discrete data during the growth process of indium phosphide single crystal, the constructed model is compared and validated, and good agreement with actual production temperature data is obtained (temperature deviation is controlled within 3%), verifying the effectiveness of the constructed model. Based on this model, this article explores the influence of temperature fluctuations of the four stage heaters on the distribution of the thermal field under production conditions, and studies the influence of temperature fluctuations of the four stage heaters on the low-temperature zone, high-temperature zone and material pipe center temperature in the furnace. The conclusions obtained have certain guiding significance for revealing the distribution and adjustment methods of the thermal field in InP single crystal furnaces in industrial production processes.