The performance of real-time (RT) precise positioning can be improved by utilizing observations from multiple Global Navigation Satellite Systems (GNSS) instead of one particular system. In this contribution, a RT precise positioning system based on actual RT GPS/GLONASS/Galileo/BeiDou observation streams is established at the Institute of Geodesy and Geophysics (IGG), Chinese Academy of Sciences (CAS). Multi-GNSS satellite orbits are updated every three (or less) hours in one parameter estimation based on IGS/iGMAS observations and then predicted for following clock offset estimation. Fixing the predicted satellite orbits, RT correction messages are generated every 3 seconds and broadcasted by processing RT observation/navigation data stream from IGS/iGMAS/AUSCORS. This system also provide real-time atmospheric delay, phase Bias, and other related correction messages. At the user side, RT Precise Point Positioning (PPP) is realized by processing RT data streams and correction messages received. A set of experiments are conducted to evaluate the performance of the system. The satellite orbit/clock results are evaluated by comparing with the multi-GNSS products from GFZ, as well as the RT products broadcasted by CNES. In addition, the user positioning accuracy and the convergence time of RT PPP based on single/multi-system observations are evaluated by 35 globally distributed stations.