The relationships of the surface roughness, hardness and elastic modulus to the friction properties were studied based on objects of a medical NiTi wire, a medical stainless steel wire and four medical β-Ti wires. The results show that the most significant factor on the friction resistance is the surface roughness, and the friction resistance has a positive correlation with it. However, the friction resistance has a negative correlation with elastic modulus and hardness. By the regression fitting, the quantitative relationships between the surface roughness, elastic modulus, hardness and friction resistance is established, that is f = (E -0.02649)·(H-0.07035)·(Ra0.80625), R2 = 0.9982.