The existing monocular-based three-point laser vision measurement system is susceptible to errors such as laser feature point 2D image detection, camera distortion, image center point coordinate, and focal length errors. Aiming at alleviating these errors, a new ranging and pose estimation is proposed. In the proposed method, the solution of the attitude angle is only related to the distance value, fixed parameters of the camera, and installation position of three lasers. First, the three lasers are controlled to calibrate the internal parameters of the monocular camera when emitting light in parallel, and the pose coordinates of the center point of the camera are calculated. Then, according to the calibration parameters of the camera at different distances, an iterative method is used to solve the minimum error. Finally, the downward tilt γ angle of the top laser is adjusted to calculate the yaw and pitch angles of the target plane. The experimental results show that the accuracy of distance measurement and attitude estimation is ensured while reducing the influence of the error term. The average error of distance measurement within a distance of 200-600 mm is 0.65 mm, and the error of yaw angle and pitch angle is less than 0.98°.