Abstract： Objective To study the internal and external maximum malleolus stresses when they landing from different heights with squat-style.Methods The subjects were 18 male professional paratroopers,wearing military special parachute boots,respectively jumped from 60 cm and 150 cm height platforms and landed with squat-style attitude to test their internal and external maximum malleolus stresses.Results For 60 cm height jumping,the average maximum stress of internal malleolus was 328.71 kPa,the average maximum stress of external malleolus was 205.92 kPa,the average maximum stress of internal malleolus was significantly greater than that of the external malleolus (t=4.005,P＜0.01).For 150 cm height jumping,the average maximum stress of internal malleolus was 365.39 kPa,the average maximum stress of external malleolus was 77.28 kPa.The average maximum stress of internal malleolus was significantly greater than that of the external malleolus (t=13.935,P＜0.01).Conclusions The height does not significantly affect the variation of internal and external maximum malleolus stress as the paratroopers landing with squat-style.The left and right maximum internal malleolus stress is respectively greater than the left and right maximum external malleolus stress.The stress differences lead to paratroopers' excessive foot pronation and are the major biomechanical mechanisms that caused ankle injury.