Abstract: In this paper, the current application and performance evaluation of pretreatment system for natural gas online analysis were comprehensively investigated. And its status of performance evaluation technology and development trend of pretreatment system after natural gas quality upgrade were summarized and analyzed. As there was no available standard method, the pretreatment system maintenance only relied on experience. In order to solve this problem, a prospective method of integration multiple evaluation was proposed, which includes evaluation of particulate filtration performance by gravimetric method, evaluation of droplet filtration performance by weighing method, evaluating the anti-sulfide adsorption performance by measuring the hydrogen sulfide content before and after the pretreatment device, and evaluating the performance of temperature and pressure control by temperature and pressure sensors.