Compression, tensile and combined tension/shear tests were performed on PA66 at different strain rates by using a universal material testing.The study shows a marked strain rate sensitivity of the yield and hardening behaviors under different loading on PA66.A modified shear-tension specimen (STS) with the material axis inclining to the loading direction at different angles (30°, 40°, 45°, 60°, 75°) was presented.The shear stress and normal stress of modified STS were investigated, which indicated that the stress component changes with the angle.Furthermore, by comparing the three yield criteria in present research with experimental yield surface for different stress states, the yield criterion that can describe the asymmetric yield strength of tension and compression and the hydrostatic pressure dependency of PA66 was established.In addition, the yield strength for different strain rates was predicted and the availability was verified by comparing the predicted value under different loading.The experimental yield of PA66 obtained by the shear-tension test method proposed in the present paper agrees well with the theoretical model, which indicates the reliability of the test method.