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Up to now,the International GNSS Service Real-Time Service (IGS RTS) is able to provide real-time orbit/clock corrections for GPS system while the corrections for other GNSS systems are being developed.Although high quality satellite orbit and clock corrections are widely available in real-time now,a high update rate,typically 1-10 seconds for satellite clock and 1-2 minutes for satellite orbits,is required which therefore requires continuous wireless connections between the correction suppliers and the users.A loss of correction data,which is not uncommon in real-time applications such as positioning in areas with signal blockages/attenuations or poor network signal strength,will degrade the obtainable positioning accuracy.Data communication cost will also be a concern for many applications particularly for precision applications with mobile devices.With the above mentioned concerns,Gao has proposed a new real-time PPP sys-tem,which can not only help bridge the gaps when users cant receive real-time corrections but also greatly reduce the communication cost.The new system requires high precision orbit prediction by numerical integration at the user end which should be investigated.This paper will implement and analyze high precision satellite orbit prediction process by numerical integration as required in the real-time PPP system.Firstly the paper will briefly introduce the structure of the new real-time PPP system.Then the generation of low-frequency satellite Initial Parameters (IP) at the sever end will be discussed,which includes the satellite position,velocity and the Solar Radiation Pressure (SRP) parameters for each satellite as well as the Earth Rotation Parameters (ERP) parameters.After that,the method for orbit prediction at the user end with dynamic models including the Earth gravitational force,lunar gravitational force,solar gravitational force and the SRP will be presented.For orbit numerical integration,both the single-step Runge-Kutta and multi-step Adams-Bashforsh-Moulton integrator will be implemented.Finally comparisons will be conducted to assess the accuracy of the user generated satellite orbits.