Abstract: To investigate the influence of rockfall shape on the peak impact force, three-dimensional rockfalls with different shapes are generated based on discrete Fourier transform and random field theory. A finite element model of rockfall impacting concrete slabs is established using ANSYS software. Combining with feature importance scores, the effects of flatness and elongation on the average peak impact force (F_max) and the effects of shape factor and roughness on the standard deviation of peak impact force (σ) are analyzed. The results show that flatness and elongation have no significant effect on F_max, and the influences of shape factor and roughness are more significant on σ. The average maximum increase in the peak impact force reaches 79.6%. The impact force without considering the shape of the falling rock is small, and it is corrected by fitting an amplification formula for the shape factor and roughness of the falling rock impact force. Finally, a case analysis is conducted, showing the shape of rockfalls has a more significant impact on the local damage of structure, while its influence on the overall response of the structure is minor.