In this paper, flume model test on local scour around piles embedded in composite sand was performed, and comparisons and discussions of such predictions of local scour depth in current China and America were also made. The test results show that the scoring progress is slow because the main scoured parts are coarse sand in the early stage. However, in the later stage, as the fine sand becomes the main scoured parts, the progress is faster. The upperlayer coarse sand can help to keep the lowerlayer fine sand from being scoured, and the thicker the coarse sand layer was slower than the fine sand will be scoured. The present design codes of China and USA both work well, but these codes often lead to a much exaggerated results. Therefore, to reflect the effects of the coarse sand on the fine sand, the scour depth should be reduced.