Abstract: The current research status of the stability characteristics of reinforced gabions is analyzed,and it is found that there are few studies on the stability characteristics of reinforced gabions considering the deflection angle. Considering its shortcomings,subjected to force analysis and derivation,a formula for calculating the critical velocity of the reinforced gabion considering the deflection angle with the undetermined drag force coefficient C_D is proposed. On this basis,a × a × a,a × a × c,a × b × c,three shapes of reinforced gabion critical velocity flume experiment and drag force coefficient experiment,the undetermined drag force coefficient under the influence of deflection angle and Reynolds number is considered. The experimental results show that the larger the deflection angle of the reinforced gabion,the lower the critical velocity;the drag coefficient of the reinforced gabion is between 0.55 and 0.84,and the drag coefficient first decreases and then increases with the increase in the deflection angle.When the deflection angle is 15°,the drag coefficient takes the minimum value;the drag coefficient of the reinforced gabion first increases and then gradually decreases with the increase of the block Reynolds number. The deduced formula has been verified experimentally,and accuracy is good,which can provide a theoretical reference for the calculation of the critical velocity of the reinforced gabion and the value of the drag coefficient.