GB/T 3903.39-2019 specifies the test method of peel strength between layers for the upper surface of footwear. Applicable to all kinds of upper materials. The standard details the test principle and tests the bonding firmness between the layers of the upper surface with the help of tensile equipment. Clarify the technical requirements of the required instruments such as Universal Testing Machine, and standardize the sample preparation, including size specifications and sampling positions. Strictly specify the test operation steps, such as loading speed and test direction, and give the calculation and representation method of the results. This standard provides a unified and scientific testing basis for evaluating the mass of the upper surface and ensuring the durability of the product.