Abstract: The improvements of sound insulation performance of six kinds of common sealing strips at the bottom of residential door are studied by using sound intensity method. The sound insulation distribution maps of the door before and after installing the six kinds of sealing strips at the bottom of the door are drawn, and the effect of the sound leakage after the installation of sealing strips is discussed. The sound insulation improvement of the sealing strip at the bottom is related to its sealing performance, and the sound insulation and sound absorption performances of the door itself. The experiment shows that the sound insulation improvement of the sealing strip at the bottom of the common residential door is 2－6 dB, and the improvement effect is significant. At the same time, this paper verifies the application of Gomports' theory in the study of sound insulation of slit at the bottom of the door. The theory has high accuracy at the mid and low frequencies, but it deviates from the experimental results greatly at the resonance frequency.