Reciprocating seals are vital components in hydraulic systems. As a kind of reciprocating seal, the glyd-ring is commonly used as a piston seal. For the sealing characteristics of aircraft glyd-ring under severe working conditions, systematic research and experimental verification are not sufficient. The liquid-solid coupling model based on mixed lubrication theory is established in order to analyze the characteristics of the glyd-ring seal in the cylinder piston. The contact stress distribution on the glyd-ring under different fluid pressures or temperatures is discussed through finite element analysis. The mechanical analysis of solids and fluids are carried out separately, and the thickness of the fluid film is continuously updated until the results of the deformation analysis converged. According to the calculation results obtained by this model, three characteristics of the glyd-ring seal (static contact pressure, film thickness, friction force) are discussed. As the fluid pressure rises, the contact pressure in the sealing area increases by a rate which is greater than that of the corresponding fluid pressure, the seal length is shortened, the fluid film thickness is reduced, and the frictional force gradually increases, this force increase is proved by test data. As the temperature rises, the contact pressure in the seal area (near the O-ring) increases by a rate which is greater than that of the corresponding fluid pressure, the seal length increases, the oil film thickness decreases, and the frictional force increases significantly.