Because gas film thickness in dry gas seal is only 3～5μm, it is very important to gas film vibration test and stability analysis. Using high precision improved version of the eddy current miniature sensor and high speed data acqui sition card, the gas film balance and vibration displacement of spiral groove dry gas seal are measured in different operating state. The gas film vibration displacement of three spiral groove dry gas seal with different spiral angle is measured in different operating state. Then the measured data is spectral analysis by dry gas seal test system based on Labview software. Experimental research shows that gas film balance displacement increases and gas film vibration displacement decreases with rising of the speed and air pressure. It exists a best spiral angle when gas film vibration displacement is minimum and the optimal spiral angle in the test is 74 degrees, which provides a guidance for the optimization design of spiral groove dry gas seal.