The invention provides a high-strength composite seal gasket used for high-pressure oil pipes. The seal gasket has a multilayer composite structure and includes, from top to bottom successively, a first surface coating layer, a first transition layer, a core layer, a second transition layer and a second surface coating layer, wherein the first surface coating layer and the second surface coating layer have excellent anti-corrosion and high-temperature resistant performances; the first transition layer and the second transition layer have two functions, one is to promote excellent adhesion between the first surface coating layer and the second surface coating layer, and the other is that pores are formed in the interiors of the first transition layer and the second transition layer, so that the first transition layer and the second transition layer have certain elasticity and has certain buffer effect under a high-pressure status, thereby avoiding rigid fracture and increasing mechanical strength of the seal gasket. The seal gasket has high mechanical strength, is anti-corrosion and high-temperature resistant, and is very suitable for high-pressure oil pipes in automobiles.