Abstract: Real time Precise Point Positioning (PPP) needs real time GPS orbit and clock product. An approach to real time PPP using regional GPS Continuously Operating Reference Stations (CORS) data and IGS ultra-rapid (IGU) product is proposed. First, real time GPS satellite clock was estimated using regional CORS data and IGU real time predicted orbit product. Then real time PPP positioning for user GPS receiver was conducted using the estimated real time satellite clock and IGU real time predicted orbit. Experiments show that the approach could be used to do centimeter level PPP positioning. And the valid service area of the proposed method could be extended to several hundreds kilometer out of the region.