Complex box is an important part that is difficult to manufacture.Using reverse design technology can effectively shorten the design cycle of complex box parts and reduce production costs.Digital measurement of box is one of the key technologies in reverse design.When making digital measurement of a complex box,a laser scanning measurement method using transfer station method was selected.The point cloud data on the outer surface of the box were directly obtained through laser scanning measurement.The shape of the inner cavity of the box is complex and difficult to measure.By pouring gypsum into the inner cavity of the box,the gypsum was taken out after it was cooled and molded,and the outer surface of the gypsum was measured to obtain point cloud data of the outer surface of the gypsum.the mass center of the gypsum was calculated,the point cloud of the gypsum surface was scaled according to the shrinkage rate of the gypsum material,and the point cloud data of the interior surface of the box were reversely calculated.Finally,the feature point matching method was used to fuse the exterior point cloud data of the complex box with the interior point cloud data to form a complete box point cloud model.According to the point cloud,the three-dimensional digital model reconstruction and accuracy evaluation of complex box parts were completed.