A laser non contact surface sensor for measuring 3D free form surface is proposed. This sensor is simple in structure and its output is linearly proportional to the measured displacement in optical principle. Because this sensor can receive the diffused light of the object in 360° direction, the inclination effect is very small. Problems of shadow effect and inclination influence are solved. The measurement range of the sensor is 4 mm, resolution is 2 μm. When object is inclined to ±85°, measurement error is about 20 μm.