The P-P technique in measuring the sound intensity is presented and the phase should be matched when using the P-P technique to measure the sound intensity. The noise sources of the running maglev train compartment are identified by using the sound intensity method. The results are studied by analyzing the transfer functions. We can drawn a condusion that when the train is running at the speed of 430km/h, the noise transmits into the compartment mainly from the wall of the train. The 1/3-octave spectrums of the sound intensity are studied and the contributions of frequency component from every measuring point are analyzed. It can be concluded that the reflective intensity below 100Hz is mainly from the wall of the train. In other spectrums, the contributions of the three points are similar.