Abstract: A series of shaking table tests on a sawdust-mixed clay site model are conducted under uniform earthquake excitation using the shaking table testing system with 9 sub-tables in Beijing University of Technology. The tests are performed using a rigid prefabricated continuous model box with dimensions of 7.7 meters long, 3.2 meters wide and 1.2 meters high. The test system is subjected to strong ground motions from El Centro record and Tianjin record. Through the horizontal longitudinal and horizontal transverse free-field shaking table tests, the boundary effect of the model box is investigated, and its dynamic characteristics and variation laws are given. The partial test results are analyzed, including the peak ground accelerations and their amplification factors, acceleration time histories and their Fourier spectra for the site responses. The test results indicate that the boundary effect of the model box is small because there is only a slight difference in the accelerations of site responses at the same elevation. With the increase of intensity of the input ground motion, the peak ground acceleration of the site response at the same test point increases, but its acceleration amplification factor decreases, and the main frequency components move from high to low frequency. It means that the soil becomes softer and the soil modulus decreases gradually with the increase of the intensity of input ground motion.