Abstract: Beam position monitor (BPM), as the most popular component in beam instrumentation system of particle accelerator, carrying not only beam position information but also other information like beam charge, is suitable for multi parameters diagnostics. This paper introduce BPM theory and numeric simulation results of pickup, discusses the feasibility of beam current measurement using BPM. Several beam experiments have been performed in the SSRF storage ring to calibrate current factor of 140 BPMs, evaluate current measurement resolution, beam position dependency and RF frequency dependency. The performance and limitation of this method was discussed based on these experiments.