I Increasing oil well production can be done by artificial lifting. Artificial removal method can be done in several ways one of which is by injecting water or called the Water Injection method. Making injection wells in this way is more effective and compared to drilling which requires a very large cost. The Water Injection method uses formation water produced by the well itself or commonly called Production Water. Centrifugal pump is one of the equipment needed in this Water Injection process where the pump serves to flow Production Water into the injection well. PT X is one of the companies that conducts oil production to increase the amount of oil production capacity so as to increase the amount of Production Water capacity from 40,000 blpd to 80,000 blpd. Therefore, it is necessary to optimize the existing pump system, by performing a re-performance calculation of the pump such as calculating Reynolds numbers, friction factors that occur, calculating the total head losses at the pump, calculating the pump adjustment NPSHa in accordance with API 610 standards to determine whether the pump is in compliance with standards and calculate variations in the number of pumps that will be used to meet the needs of the company. From the recalculation results, the results are that the number of pumps used is as many as seven pump units can produce 2,450 Usgpm or 84,000 blpd with a head of 2480 ft or 1,075 psig greater than the maximum pressure in the discharge header which is 950 Psig, pump specifications PAT 364 according to API-610 Requierement. So that the pump is safe to use to fulfill production activities.