A three-dimensional point cloud upsampling method includes: dividing a three-dimensional point cloud into overlappable point cloud blocks which have a fixed number of points and are capable of covering all the points; extracting hierarchical features according to point coordinates in the point cloud blocks; achieving point set feature expansion of the extracted hierarchical features by using multi-scale heat kernel graph convolution; and reconstructing point coordinates in an upsampled three-dimensional point cloud from the expanded features. According to the present disclosure, detail information enhancement with different fine granularities can be performed on the three-dimensional point cloud which is sparse and nonuniformly distributed in the space, and at the same time, good stability is provided for overcoming potential noise disturbance and local deformation. The method can promote the uniformity of spatial distribution of the upsampled dense point cloud, and ensure the accurate representation for a geometric structure of a target object.