Abstract The development and advancement of microelectronics industry is very drastically. So, the key to create new technology of process and it's costs can be cut by simulating the performance of these equipments. The reactor of chemical vapor deposition (CVD) is important to semiconductor production process.. This research use numerical method to study the process parameters of low-pressure chemical vapor deposition (LPCVD) of Tungsten (W).In this simulation, the CVD reactor modeling are constructed and discreditzed by using the implicit finite volume method. The grids are arranged in a staggered manner for the discretization of the governing equations. Then, the SIMPLE-type algorithm will be used to solve all of the discretized algebra equations. In this research, the reactor is an single wafer and cold-wall system. The nozzle position is adjustable from 100 to 250mm.The nozzle-to-wafer distance is adjustable by changing the height from 30 to 120mm.The temperature and pressure in the reactor system can be setup with susceptor temperature 300~600 and pressure 0.5~8Torr. The results show that the flow in the reactor may depend on the flow rate and nozzle position. An effective means to avoid unstable is to reduce the susceptor temperature and system pressure due to the effects of buoyancy force and recirculation.