In order to enhance the precision of the three-dimensional (3D) measurement system based on the laser sensors, an on-line calibration process based on structure parameter is proposed in this content. In this method, the structure object with known parameters is measured by the laser scanner, with its model being established within the laser scanner coordinate system and inertial measurement sensor coordinate system separately, and the linear feature on the scanned plane being extracted, then the relative position and orientation relationship is calculated with the constraint conditions of the structure parameters. The initial value calibration experiment is conducted on the 3D measurement system, then the initial values is used to conduct on-line calibration experiment, and the average relative error of measurement is below 0.9%, which means the calibration and measurement method is accurate and can adapt to different work conditions.