A　branched　polycarboxylate　superplasticizer　(BPCE)　was　synthesized　via　copolymerization　of　polymerizable　active　center,　isobutenyl　polyethylene　glycol　(IPEG)　and　acrylic　acid　(AA).　To　investigate　the　effects　of　chain　transfer　agent　on　the　performances　of　BPCE,　a　series　of　BPCEs　with　different　molecular　weights　were　further　synthesized　by　changing　the　addition　amount　of　chain　transfer　agent,　i.e.,　thioglycolic　acid　(TGA).　The　characteristic　molecular　structures　of　BPCEs　were　determined　by　Infrared　Spectroscopy　(IR)　and　viscosity　method.　Furthermore,　the　dispersing　capacities　and　adsorption　behaviors　of　BPCEs　in　cement　pastes　were　probed.　The　result　showed　that,　the　paste　fluidity　and　adsorption　amount　both　presented　a　trend　of　first　increase　and　then　decrease　with　the　increase　of　TGA/IPEG　proportion,　and　the　maximum　appeared　at　the　TGA/IPEG　proportion　of　0.15　(M　=　96314　g/mol).　The　hydration　products　of　cement　pastes　containing　BPCEs　at　different　curing　ages　were　measured　by　X-Ray　Diffraction　(XRD),　showing　that　the　introduction　of　BPCE　caused　the　delay　of　initial　hydration　which　presented　some　retardation,　and　this　trend　was　shown　most　significantly　at　the　TGA/IPEG　proportion　of　0.15.　The　aim　of　this　study　is　to　suggest　that　moderate　dosage　of　chain　transfer　agent　for　the　synthesis　of　BPCE　is　beneficial　to　achieve　good　dispersing　and　adsorption　effectiveness.