Abstract: To solve the problem of the automatic inspection of the internal threads of a rotating sleeve operated by an aerospace vehicle, especially when the surface of the internal thread has oil pollution and rust, simply using optical image detection method was difficult to solve. The flat gas was blew inward internal thread to form the turbulence output mapping the appearance of the internal thread, and then the turbulence characteristics of internal thread was detected by Doppler laser. The data characteristics were investigated in the stretching process and compression process of internal thread gas turbulence. The gas turbulence data was dealt with box line chart method. A standard template database of the box line chart of internal thread turbulent was established. The detection data was compared with the standard template. The result shows that when the threshold value of outliers is set to be 7%, the detection accuracy is 99.3%. Gas turbulent laser Doppler method for detecting internal threads is feasible, and overcomes the surface oil pollution and other difficulties, meets test requirements totally.