In this study, key properties of polyethylene resin and HDPE GM were tested for comparing their stress crack behaviors. Stress cracking time was differed from each type of resins and products. The failure times of ESCR test were too long compared to SP-NCTL’s. The SP-NCTL results of RWOA was failed earlier than RWA‘s, GM1’s and GM2’s. But there was no difference between each sample of the results of ESCR test within short term testing duration. The ESCR test was influenced by stress relaxation during the test. The SP-NCTL test is reasonable for verifying stress cracking behavior and construction quality control. According to this study, ESCR test is not appropriate for determining the stress crack behavior, but SP-NCTL test is better test method for predicting the stress crack behaviors of HDPE GM.