To understand the history of paleoclimate changes in the Gulf of Thailand, we performed systematic geochemical and mineralogical study on the core T155 collected from the Gulf of Thailand. The rare earth element index of (La/Sm)ucc-(Gd/Yb)ucc diagram for sediments indicate that the sediment source in the southwestern Gulf of Thailand was relatively stable since the Holocene and mainly from the Malay Peninsula, and the coastal current controlled by the seasonal monsoon was the main driving force. Based on the proxies of kaolinite/(chlorite+ illite), chemical alteration index (CIA) and potassium aluminum ratio (K/Al) in the core T155，this study divided the Holocene paleoclimate evolution into the following two stages, ①The early-middle Holocene (12 000 cal a BP-6 500 cal a BP): the values of kaolinite/ ( chlorite+ illite) and CIA were high, indicating the strong East Asian summer monsoon in this period. During this stage， kaolinite/( chlorite十illite) value and CIA appeared two low value periods, corresponding to two high value of K/Al, which occurred in 11 200 cal a BP- -10 500 cal a BP and 8 500 cal a BP-7 500 cal a BP, respectively, indicating the response of the Gulf of Thailand to two global millennium scale climate events (the younger dryas event and the 8.2 ka cold event). ②After the middle Holocene (6 500 cal a BP): the values of kaolinite/ (chlorite+ illite) and CIA have decreased significantly, indicating that the East Asian summer monsoon has gradually weakened during this period. At the period that from 3 200 cal a BP to 1 800 cal a BP，the geochemical and clay mineral indexes showed an obvious low value，which corresponds to the “Pulleniatina Minimum Events” in the tropical sea area, implying the good regional response to global climate change in the Gulf of Thailand.