The pressure sensitivity of pressure-sensitive adhesive is the performance of its adhesive properties. Its adhesive properties are composed of four factors: fast tack (A), adhesion (B), cohesion (C) and adhesion (D). The composition, the fast adhesive force (A) refers to an interfacial peeling force exhibited when the adhesive tape is separated from the adherend at the lightest pressure and at the fastest speed. It can be understood as the initial viscosity, the viscosity and the ability of the pressure-sensitive adhesive to infiltrate the adherend, etc., which is difficult to define strictly. The adhesive force (B) refers to the peeling force which is exhibited between the adhesive tape and the surface of the adherend after proper bonding, and the size thereof determines the adhesive property of the adhesive tape. Cohesion (C) is the cohesive strength of the adhesive layer, which is related to the inter-molecular force, the intermolecular bond, the molecular size and the arrangement of the molecules. The adhesive force (D) is the adhesion between the pressure sensitive adhesive and the substrate or the adhesion between the pressure sensitive adhesive and the primer and the primer and the substrate. Because the relationship between these four forces should satisfy A<B<C<D, the properties and dosage of each component and its influence on the adhesion characteristics should be strictly observed when designing the pressure-sensitive adhesive formulation.