Abstract: Monte Carlo simulations are adopted to study the distribution of the nonlinear electric field in the reaction field of diamond film growth at low temperature via EACVD. The results indicate that the distribution of the electric field near the anode in the reaction field changes by exponential rules. Under certain bias voltages with the changing of pressure, there will be a reverse electric field near the anode. This reverse electric field is very important to some positive ions in diamond film growth at low temperature.