Based on the seawall protection engineering,modified the original rigid structure with the hinged fascine mattress technique,a series of tests were applied at the indoor wave flume to determine the minimum stable thickness of hinged fascine mattress.The results show that the minimum stable thickness of hinged fascine mattress under regular wave is much less than that under irregular wave although both the regular and the irregular wave have similar wave parameters.The wave period is as important as the wave height when determining the stable thickness.The new fitting formula about the minimum stable thickness of hinged fascine mattress was obtained based on the test results and previous formulas.