The ejector has advantages of small size, no moving parts, no parasitie energy consumption, ete. It is becoming an idealsolution for hydrogen reeycling in hydrngen fuel eells. However, it is difficult to mateh and optimize the ejcector with the stack due to thehigh coupling between the ejector's circulating fluid and the supply fuid. In this paper, the combination of computation fluid dynamic(CFD) calculation and experiment is used to obtain multiple sels of different nozzle exit position(NXP) and working conditions underthe eoupling change of ejector ejeetion fluid pressure and back pressure under fuel cell variable load conditions. The internal pressurefield and velocity field of the ejector explore the evolution of the influence of the NXP variable operating conditions on the ejectorperformance. Results show that the increase of primary flow pressure is helpful to improve performance of the ejector. When the primarypressure is 4 bar, the ejeetion ratio reaches a peak of 2.43 when NXP is -15.6 mm. Meanwhile, based on the research results, thispaper utilizes numerical analysis to achieve the optimal NXP judgment method of the ejector under variable working conditions, which ishelpful to the matching design and optimization of the ejector and the stack under wide working conditions.