Abstract: According to modeling of prototype,it was deduced that as long as the footings used in centrifugal and gravitational tests were different,the bearing capacity obtained in centrifugal tests was always larger than that obtained in gravitational tests,namely particle size effects always existed in centrifugal tests.And with the ratio of footing width to mean particle diameter increasing,the results of centrifugal tests were gradually close to those of gravitational tests.When the ratio was large enough,the difference between the centrifugal and gravitational tests would be so small could be be ignored.So using modeling of models,a series of loading tests using Toyoura sand were conducted in a centrifuge to determine the particle size effects on bearing capacity of strip footings.In the tests,the model footing width was changed on a larger scale,and the ratio of the maximum width to the minimum was 5.The upper limit of the ratio is 291.Based on the test results,an index was introduced to quantitatively measure the influence of particle size effects on the test results.And the influence decreased with the increase of the ratio of footing width to mean particle diameter.In the tests,particle size effects on the results could be ignored when the ratio of footing width to mean particle diameter was larger than 233.