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Due to the precision of BDS orbits and satellites clock,BDS PPP need long time to convergence to centimeter accuracy than GPS PPP.Combined BDS/GPS PPP can benefit from more visible satellites and enhanced satellite geometry distribution,which can accelerate the convergence speed of PPP.In this contribution,Combined BDS/GPS PPP and its integer ambiguity resolution were investigated.Using data set of 8 MGEX stations,the visible satellites and PDOP between GPS constellation and BDS/GPS constellations were analyzed.The results show combined BDS/GPS constellations can increase visible satellites and reduce PDOP.The improvement rate of visible satellites and PDOP is 89% and 31%.Then,the positioning accuracy and convergence speed of single system PPP and combined BDS/GPS PPP were compared.For PPP hourly solutions,the positioning accuracy and convergence time of combined GPS/BDS PPP is better than single system PPP solutions.For PPP daily solutions,however,the positioning accuracy is notsignificantly improved.Finally,the integer ambiguity resolution of PPP was conducted.Only the GPS ambiguities were fixed and leaved BDS ambiguities as float values.The experiment results with MGEX BDS/GPS dataindicate that combined GPS/BDS PPP with GPS integer ambiguity resolution can further improve positioning accuracy of PPP hourly solutions.Comparing with float solutions,the positioning accuracy is improved by 59.1% in N component,87.0% in E component and 39.1% in U component.