Aiming at the crucial issues of serious friction and wear and large leakage in the key friction pair of the aviation plunger pump,the influence factors of pressure flow and shear flow were introduced to correct the Reynolds governing equation of the clearance flow,and then the finite element method was used,considering the elasticity deformation of the plunger pair,the lubrication and leakage characteristics of the plunger pair were analyzed.The results show that:the maximum oil film pressure considering the elastic deformation of the bushing is smaller than that of the rigid bushing,and the oil film pressure which position is close to the both ends of plunger in axial direction are slightly larger than that without considering elastic deformation;the minimum oil film thickness of rigid bushings is smaller than that of elastic bushings.Considering the elastic deformation,the thickness of the oil film increases rapidly at both ends in the axial direction,and the relatively flat in the middle is “opening dustpan-shaped”,while the oil film thickness of the rigid bushing in the axial direction is a straight line,and the largest bushing deformation in the circumferential direction is about 2 times than that in the axial direction.When the pressure difference and the eccentricity of the plunger increase,the leakage ratio of a single plunger pair tends to increase approximately linearly,when the unilateral clearance increases above 3 μm,the leakage ratio increases significantly.