Liquid composite molding (LCM) is a leading process for manufacturing polymer materials. The LCM process is optimized by designing injection/mold temperatures in actual production. The variety rule of technics parameters such as temperature, curing degree, viscosity, and pressure in the non-isothermal LCM process is the theoretical basis for injection/mold temperatures design. Due to the typical closed mold operation, numerical simulation is the main tool for studying the LCM process. This article used numerical simulation to study the LCM process of typical 3D component. The variation of technics parameters is studied by setting different injection/mold temperatures. This study finds that temperature gradients and curing degree gradients are easily generated along the resin flow direction inside the component. Increasing the injection temperature is more significantly than mold temperature to reduce the resin viscosity and the maximum pressure inside the mold. Meanwhile, increasing the mold temperature is more beneficial than injection temperature for reducing the surface force of the mold wall. Therefore, it is necessary to optimize the injection/mold temperatures in different application scenarios.