The invention relates to the technical field of aircraft composite material interlayer tensile stress design, and provides a method for determining an allowable value of an interlayer tensile stress design of an airplane composite material, which comprises: 1, determining influence parameters including a B reference value coefficient, an environment, a laying proportion, a thickness, a corner radius joint thickness, a damage and a thermal cycle influence coefficient; 2, determining an interlayer tensile stress design allowable value calculation formula based on the B reference value; 3, determining a test matrix; 4, determining a test environment standard, an environmental influence test moisture absorption saturation determination standard, a thermal cycle influence test cycle index and temperature spectrum, and a test piece damage determination standard; 5, performing a test by referring to an ASTM D6415 test standard to obtain an interlayer tensile stress average value and a B reference value initial value; 6, calculating a B reference value and each influence parameter; and 7, calculating an interlayer tensile stress design allowable value. The method is high in accuracy, highin universality, low in test cost and high in test efficiency.