The awareness of protecting traditional culture and humanistic landscapes is increasing year by year, and the protection of ancient gardens is becoming more and more a consensus among people. This paper takes the architectural profile of Guyi Garden as the research basis, introduces the specific application of 3D laser scanning technology, plans the scope of architectural data acquisition in Guyi Garden, and designs the corresponding architectural data acquisition program. With respect to the acquired point cloud data of GuYiYuan, the bilateral filtering algorithm is used to reduce the noise of the data, the curvature thinning algorithm is combined to reduce the point cloud data of the buildings in GuYiYuan, the point cloud data are spliced based on the connection point, and the ICP algorithm with the introduction of the optimization of the rotational angle constraints is introduced to realize the alignment of the point cloud data. In addition, the shadows generated from the point cloud data are removed by combining the relighting method, and the linear transformation method is also used to globally correct the texture image generated from the point cloud data. The point cloud density was reduced from 0.95m² to 0.01m² when the thinning rate was increased from 8% to 96%, and the alignment error of the improved ICP algorithm under 25dB Gaussian white noise was only 0.083*10-4mm. The maximum error accuracy of the two-dimensional model of Yiyi Nodang generated based on the point cloud data was only 0.007m, and the error of the three-dimensional model was controlled to be within the range of ±9mm. Accurate architectural data can be obtained through the use of 3D laser scanning technology, leading to a new method for digitally preserving historical buildings.