The invention provides a valve leakage testing system and a valve leakage testing method based on infrared thermal imaging technology, wherein the valve leakage testing system and the valve leakage testing method belong to the field of valve monitoring technology. The valve leakage testing system and the valve leakage testing method settle the following technical problems in a valve: high difficulty in realizing middle-and-long-distance leakage testing, infrared thermal imaging technology limitation by interference of emissivity non-uniformity, infrared thermal imaging result interference by temperature condition change, relatively low valve leakage testing precision, relatively high testing cost, etc. Middle-and-long-distance pressure-testing leakage testing of the valve is searched. Advantages of non-contact temperature testing and quick capture for overhot points in infrared thermal imaging technology are applied in leakage testing. Accurate measurement for leakage point position and grading analysis on leakage amount are realized. A technical problem of interference caused by emissivity non-uniformity is settled. Furthermore the valve leakage testing system and the valve leakage testing method have advantages of high testing precision, reasonable testing cost, and good popularization prospect.