The increasing interest in particle shape influence on granular mechanics necessitates a fast and robust particle shape generation method. We describe a new approach based on rotation-invariant spherical harmonic (SH) analysis. The core of this method is to construct morphology features at various length scales and superimpose them together to form the overall morphology. This method uses four rotation-invariant SH factors to construct SH coefficient matrices. We quantify particle shape at form, roundness, and compactness to establish the linkage between SH factors and traditional shape parameters. It is found that SH factors effectively control particle features at different scales. This method has a great potential to facilitate the research on granular mechanics considering particle shape effects. (C) 2018 Elsevier B.V. All rights reserved.