From ways that can help in this regard, the use of methods to prevent emissions to the surrounding environment. Due to the size of dust particles, none of the solid-gas emissions systems, such as cyclones, filters or cleaning fibers can be useful in this way. These systems have low efficiency in this range, and in addition it has a lot of pressure drop and quickly become saturated. But the electrostatic precipitator instruments in addition to high performance, they can remove very small particles of pollutants. In this project the performance of an electrostatic precipitator with three wire electrode and the drain electrode collector plate has been investigated and the effect of different operating parameters on its operation has been studied by mathematical modeling. A two-dimensional geometry of the problem has been considered and the electric field and the concentration of particles have been simulated by solving the corresponding equations and obtained by a computer program. Needed data to run the program, including gas flow rate, voltage and current of an electrostatic precipitator, the concentration of the incoming particles, mobility diffusion coefficient, device dimensions and the results of a computer program include sediment maker in various parts of the electric field, the voltage in different parts of sediment concentration and returns the number of particles have been collected. As it comes from the simulation and calculation, when the space variables had been considered, at low voltages with lower diffusion coefficient of 30 to 0.6 the collection efficiency of sediment maker increased about 2.3 percent and it increased 1.5% as diffusion coefficient decreased from 10 to 0.6 and at high voltages did not affect diffusion coefficient change and at the highest state it had been caused 0.06% increasing of efficiency. If the applied voltage and Space are held constant (20000 volt.), the more increase of diffusion coefficient, the more decrease the efficiency of the sediment maker and collection efficiency around 1.3% was decreased as diffusion coefficient give change from 0.6 to 30. By changing the voltage from 7000 to 10,000 volts at constant diffusion coefficient of 30, sediment maker Collection efficiency 0.016% and the residual voltage of 7,000 to 20,000 volts, Collection efficiency was increased 0.027%. Using second geometry which includes 9 discharge electrode wire had not a great impact on improving the collection efficiency and was caused 0.11% increasing at the highest state. The results are consistent with the actual values, the difference is negligible due to the simplifying assumptions in solving equations and simulations of the system. Key Words: Electrostatic precipitator, Space charge density, Discharge electrode, Collection efficiency.