The invention provides an optimization method for the back side pressure in the tungsten deposition process. The method includes the steps that the back side pressures in the steps of pre-deposition, nucleation and bulk deposition are compared with the yield, changes along with the back side pressures are found, and the changing result of the yield or the uniformity is obtained; the optimal values of the back side pressures in the three steps are obtained; a preset shutdown maintenance threshold value of the number of using days is set for a heater; when the value of the number of the using days of the heater is reached, the heater is detached and inverted, and the surface of the heater is soaked in hydrogen peroxide solution; after a preset cleaning time, the heater is taken out and wiped with deionized water and isopropyl alcohol; a back pressure groove of the heater is viewed, and it is guaranteed that tungsten residues have totally fallen off; the heater is assembled again, and the tungsten deposition process is executed with the optimal values of all the back side pressures. Through the method, the optimal back pressure conditions in different steps are obtained, the optimal back pressure optimization conditions can be utilized, the back side pressure of wafers is controlled and stabilized, and the step coverage rate is increased.