In the present work, the effect of crosslink density on HTPE networks has been studied in swelling, thermal and mechanical properties. The solubility parameters of HTPE PUs were obtained by swelling test. They depended on the molar ratio of N-100 and IPDI and equivalent ratio. It was decreased as the content of N-100 was lowered. The thermal characteristics of the network polymer were examined by DSC results. Thermal behavior of HTPE PU network depended on by dangling chain and chain folding in the series using N-100, with NCO/OH ratio as 1.0, 0.8, 0.6. However, when we performed experiment with IPDI and N-100, with NCO/OH ratio as 1.0, the thermal properties depended on M-c. Moreover, using IPDI with N-100 showed enhanced volume specific energy than using only N-100 in tensile test due to strain induced crystallization.