This study is aimed at developing of the flex resistance testing process at low temperature with the waterproof fabric to suit the military environment and is designed to fit for the purpose of the waterproof materials in order to optimize the test method by finding out matters in order to improve from another and through previous studies. The novel test method, which has been applied to flex resistance of existing waterproof materials, was improved and consequently, differentiated test results could be obtained according to the test temperature, sample size, and flexing method as well. We acquired that performance of the military requirement could hardly be met just by presenting the materials or merely 2~3 layers when the quality criteria for high functional water repellent fabrics were applied from the test of 8 samples. The PTFE(Polytetrafluoroethylene) is preferred to the PU(Polyurethane) as waterproof materials in the extremely low-temperature environment, but durability under the low-temperature environment may be varied depending on film thickness or laminating technique even if the materials are identical. Therefore, in addition to the material or texture, the test method capable of reflecting durability under the low-temperature environment should be suggested, and the newly designed test method proposed in this study. The water resistance measurement and the test method following flex resistance with the expanded range of flex will enable the differentiable test of the samples according to the number of flexing. This study is meaningful in that it suggests a novel test method capable of establishing a basis of deciding suitable material when selecting military goods made of the waterproof material by properly improving the test method.