Abstract: Hypersonic boundary layer transition is one of the key basic problems. To study the hypersonic boundary layer transition, an experiment at M=5 with a flat plate model was conducted. PCB dynamic pressure sensors were used along flow direction in the center of model to acquire fluctuating pressure time series. POD(proper orthogonal decomposition) analysis method was introduced to hypersonic fluctuating pressure data processing, and the single point of POD analysis method was developed. It is proved that the peak position of root mean square value of the fluctuating pressure data reconstructed by this method which has strong adaptability can characterize the transition position.