Abstract: This paper conducted a wind tunnel experiment at Ma=3.85,during which a continual blowing process was finished at the sidewall compression inlet with designed Ma=6 and starting Ma=2.5,when attack angle changed from 0° to 8°,and again to 0°.Experimental results show that,in the case of Ma=3.85,attack angle=0°,the inlet starts smoothly,and the pressure distribution is consistent with numerical simulation to a large degree.In the dynamic process of attack angle changing from 0° to 8°,when it increases to 5.7°,the inlet fails to start.In the dynamic process of attack angle changing from 8° to 0°,when it decreases to 5.4°,the inlet succeeds in startup.What's more,with the increase of attack angle,the flow coefficient decreases when the inlet starts,and it decreases sharply when the inlet doesn't start.When the attack angle changes from 0° to 4°,and again to 0°,the inlet starts in the entire process.