The selection of completion fluid system is very important for the efficient development of production wells. How to reduce the influence of human factors on the selection result of completion fluid and improve the rationality of the selection result directly affects the development effect of the oil field. Four factors affecting the selection of completion fluid system are comprehensively optimized. The weights of four factors affecting the selection of completion fluid system, including corrosion performance, inhibition performance, reservoir protection performance and system pH value, are studied using AHP(Analytic Hierarchy Process). Based on this, a rapid optimization method of oil field completion fluid system is established using fuzzy matter-element method. According to the calculation, the influence weights of four factors on the selection results are 0.157 0, 0.272 0, 0.482 8, 0.088 2 respectively. The rapid optimization method is used to guide the selection of completion fluid system in KL-X oil field, and the stealth acid completion fluid is selected as the optimal completion fluid system. Besides, the oil field has low reservoir contamination and desirable production capacity. The rapid optimization method of completion fluid had been successfully used to guide the selection of completion fluid in 7 oil fields in Bohai, and the average production was 23% higher than the production allocation.