Considering the friction and lubrication factors of the piston with rectangular texture， the dynamic damping characteristics of inflatable dual cylinder hydraulic damper are studied. Initially， the mathematic model of the damping characteristics and the dynamic pressure lubrication equation of the double-tube hydraulic shock absorber is establised. Then， the restore and compression strokes equations are calculated. The upper chamber pressure and the lower chamber pressure are obtained， and the Reynolds cavitation boundary condition is adopted， then the upper cavity pressure and the lower cavity pressure are used as the initial pressure. After that， the Reynolds equation based on five-point difference formula is discreted and the Reynolds equation by successive over-relaxation （SOR） method is calculated. Based on the above calculation， the value of the oil film friction damping force can be obtained. The influence of friction damping on piston speed， texture depth， radius and axial width of piston and other factors is analyzed， and the influence of friction factors on damping characteristics of the damper is studied. It is found that the oil film friction between piston and cylinder increases with the increase of piston velocity， texture width and piston width； as the texture depth increases， it first increases and then decreases； as the oil film thickness increases， it decreases； the piston radius has no obvious effect on the friction； and the corresponding factors affect the dynamic damping characteristics of the shock absorber.