Abstract: According to the definition and formula of maximum force plastic elongation of metallic materials in GB/T 228.1—2010 standard, a new measurement method of maximum force plastic elongation of metallic materials was established based on the physical principle of material deformation and unloading law. The results show that the method not only conformed to the definition of maximum force plastic elongation in GB/T 228.1—2010 standard, but also overcame the shortcomings of extensometer measurement method.