Based on the principle of pulse ranging, we obtain bridge point cloud data by 3D laser scanner at different cases, and acquire deformation information of key components in this bridge by qualitative and quantitative analyses of point cloud data. In this paper, a new method based on target point cloud is proposed to get precise deformation of key components by fitting the center coordinate through the outline point cloud of circular target. The calculated results are compared with the results of the displacement transducer measurement and the finite element model (FEM) analysis. Comparison results show that the proposed method combined with the bridge deformation data acquired by point cloud has higher accuracy, and it avoids the disadvantage of single point cloud measurement that cannot get the overall deformation of the structure.