A　new　Precise　Point　Positioning　(PPP)　service,　called　the　PPP-B2b　service,　has　been　implemented　in　the　BeiDou-3　Navigation　Satellite　System　(BDS-3),　which　brings　new　opportunities　for　time　transfer.　However,　the　solution　using　the　traditional　PPP　method　with　the　PPP-B2b　correction　still　absorbs　some　unknown　errors　and　needs　reconverging　when　there　exist　abnormal　data.　We　developed　a　new　receiver　clock　model　to　improve　PPP　time　transfer　using　the　PPP-B2b　correction.　The　traditional　PPP　time　transfers　using　PPP-B2b　with　BDS-3,　Global　Positioning　System　(GPS),　and　BDS-3/GPS　(Scheme1)　are　compared　with　the　corresponding　time　transfer　with　the　proposed　clock　model　(Scheme2).　The　results　show　that　GPS-only　PPP　is　not　recommended　because　of　low　accuracy　of　2　ns.　BDS-3　or　BDS-3/GPS　PPP　time　transfers　in　Scheme1　can　realize　about　0.2　ns　accuracy.　When　the　new　clock　model　is　applied,　the　accuracy　can　be　improved　by　up　to　45%　and　39.8%　for　BDS-3　and　BDS-3/GPS　PPP,　respectively.　The　proposed　clock　model　can　significantly　improve　the　short-term　frequency　stability　by　57.4%,　but　less　for　the　long-term　stability.