The unique mechanical behavior of polyline crease (PLC) origami structures inspired by the Tachi-Miura polyhedron (TMP) is investigated. We explore the potential usage as mechanical metamaterials that exhibit negative Poisson's ratio, self-locking mechanism, and load capacity simultaneously. Poisson's ratio, locked folding ratio, dimensionless force and folding ratio relationship, and elastic-plastic response during its compressive process (rigid folding motion or plastic bending/buckling) are investigated analytically and experimentally, respectively. The effect of original folding angle and the length-to-height ratio on negative Poisson's ratio, locked folding ratio, dimensionless force, deformation modes, and the mean compression force are also considered. Based on the experiments, an approximate theoretical study has also been conducted, which shows a reasonable correlation with the experimental results. The results are significant to guide the engineering applications of PLC self-locking origami structures.