The inserted-board air flow inlet distortion test shows that dynamic pressure at the engine inlet exit section can be divided into undisturbed, mixing and low pressure areas. The main turbulence flow power is distributed in mixing areas, with the value characteristics of low frequency distribution and wide range. It is basically in a normal distribution. The main power is distributed within 100 Hz. Its scale is 6 times higher than that of low- pressure area, and is the main area that affects the distortion degree. Also, the turbulence distributions of other two areas are analyzed and an analyzed result is obtained. It is discovered that with the inserted-board raised and especially when the engine operation point is moving to surge boundary, many dynamic pressure frequencies will gather to a small range, the low frequency wave power will increase in large scale, and full of all distortion area. At last, it arouses the engine stall. The primary analysis indicates that in air inlet the airflow presents self-excitation vibration during the trouble by strong distortion.