Abstract: The influence of foundation depth on the particle size effects of the circle shallow foundation in centrifuge tests on bearing capacity is studied by modelling of models. In the tests, the ground is made by the river sand whose grain diameter is adjusted by sieving and the mean grain diameter is 0.6 mm. The diameter of the model foundation changes from 5 to 40 mm and the ratio of the foundation diameter to the mean grain diameter is 8.3 to 66.7. The ratio of the depth to the foundation diameter is 0, 0.5 and 1.0, respectively, and the equivalent foundation diameter is 200 to 1500 mm. The evaluating index is used to discuss the particle size effects in the test. The results show that the influence of the particle size effects decreases with the increase of foundation depth. Based on the test results, the figure indicating the scope of the particle size effects is deduced, and it can be used to choose the reasonable model foundation size and the ground materials.