With great accuracy and high precision, the three-dimensional scanning technology has been preliminary applications in workpiece measurements, volume measurements, etc. However, for the objects of large size and low texture characteristics (like transmission line), the three-dimensional point clouds are more sparse, the matching accuracy is still problematic, and the measurement accuracy cannot meet the requirements of the special high-voltage grid construction, which means that its application may have some difficulties in this regard. In order to solve the above problem, the paper establishes the mathematical model of the binocular camera system. The accuracy of the image matching cost calculation is improved by improved Census transform and Gaussian weighting operation. Combined with the image edge preserving filtering method based on texture information, the dense point cloud of the target surface is calculated, and the 3D surface reconstruction of the measured target is realized by splicing the dense point cloud. Through the 3D measurement experiment of 220 kV grid infrastructure, the results show that the measurement error is less than 1mm. the 3D measurement method and system proposed by the papers, which meet the basic quality design and acceptance requirements of transmission line project, can be widely used in the power grid infrastructure project, to improve the accuracy of acceptance.