A series of block polyurethane ureas based on different hard segment structures and contents were prepared, using PEPA as soft segment, four diamine chain extenders and three diisocyanates as hard segment. Effect of hard segments on the properties of PUUs were investigated by FT-IR, TG, DSC and stretching test. The results show that hard segments with flexible and rigid structures can improve mechanical properties as well as thermal properties and micro-phase separation of PUUs under conditions of the same soft segment structure and similar hard segment contents. PUU samples with MDI and ODA as hard segment exhibit best properties. Additionally, hard segment contents show obvious effect on properties of PUUs with the same soft and hard segment structures. With the increase of hard segment content, the tensile strength and micro-phase separation increase first and then decrease, while the 5% mass loss temperature and elongation at break decrease. The PUU sample prepared with the mole ratio of PEPA/MDI/ODA 1∶1∶1 (the hard segment content of 31.7%), exhibits best properties such as the tensile strength of 51.5 MPa, elongation at bread of 709% and 5% mass loss temperature of 282.7 ℃.