Abstract: The ultra low emittance light source requires that the resolution of the beam position monitor (BPM) system reaches sub-μm magnitude. Under the laboratory conditions, the resolution of BPM electronics can reach the sub-μm, but the mechanical vibration of the BPM detector in the on-line machine will be an important factor to limit the resolution of BPM system to subμm. In order to meet the requirements of the 0.1 μm resolution of the BPM system for the High Energy Photon Source (HEPS), based on the BPM system in the BEPCⅡ, the comprehensive analysis including environmental vibration and beam data by using the power spectrum method was carried out to explore the factors that will affect the resolution of the BPM system. This paper begins with the relationship between the traditional measurement standard of BPM system resolution and the power spectrum. By analyzing the working principle of the BPM system, the location environment of BPM system and the measurement of the mechanical vibration level around BPM system, the low frequency spectrum of the BPM data can be obtained. The spectrum composition and analysis results of the BPM data show that the cable transmission will cause the rising of the spectrum baseline; the BPM detector is directly affected by the environmental vibration; the vibration of the characteristic frequency of the quadrupole magnet causes the rising of the peak value of specific frequency of the whole storage ring BPM data by the beam vibration. Combined with beam dynamics, the vibration source points can be inferred from the BPM data.