Abstract: To study the bearing characteristics of single pile and pile groups under horizontally and vertically excitating dynamic loads, a dynamic test plan is designed for single pile, two piles, three piles and four piles in multi-layer soil under horizontally and vertically excitating loads. The pile-head displacements of single pile, two piles, three piles and four piles are obtained from field test data, and the variation laws of the pile-head displacements with excitating frequency and pile number are analyzed. Based on the test results, the horizontal and vertical stiffnesses of single pile, two piles, three piles and four piles are given, and the variation of pile-head stiffness with the number of piles and excitating frequency is analyzed. The dynamic efficiency coefficient of the pile group is obtained through the stiffness, and its variation laws with the number of piles in the pile group and vibration frequency are analyzed. The test results may provide valuable data for simplifying the theoretical methods and verifying the relevant models through changes in displacement, pile-head stiffness and interaction coefficient of pile groups.