Aiming at the plane angle insite measurement requirement, a noncontact measuring device for plane angle is developed based on the diffuse reflection measurement features of the laser displacement sensors. The spatial coordinate calibration method of the laser displacement sensors are proposed that combines the coordinate measuring machine and position sensitive detector, an accurate measurement model for plane angle is constructed. The Montel Carlo method is used to evaluate the uncertainty of the plane angle noncontact measurement device, and the result is U=0.044°~0.046° (k=2) for the angle measurement range of ±25°. The performance verification test, repeatability test and stability test were performed to examine the specifications of the noncontact measurement device. The results show that the absolute indication error, repeatability and stability of the device are less than 0.036°, 0.004° and 0.021° respectively in the measurement range of ±25°. The test results demonstrate that the noncontact measurement device for plane angle based on laser displacement sensors is accurate, reliable and has the application prospect for the insite measurement of plane angle.