The oceanic meridional overturning circulation (MOC) is a key player in the global climate system, while continental topography provides an essential backdrop to the Earth's climate. In this study, we investigate the influence of various mountain ranges on the global thermohaline circulation through a series of coupled model experiments. Our findings reveal that the Tibetan Plateau (TP) exerts the most significant impact on the global thermohaline circulation, serving as a necessary condition for the establishment of the Atlantic MOC (AMOC) and a sufficient condition for the collapse of the Pacific MOC (PMOC). Additionally, the Antarctic continent plays a vital role in facilitating the TP to form the AMOC. Although no individual mountain range can give rise to the AMOC independently, the TP alone can suppress the development of the PMOC. Through altering the global hydrological cycle, the TP may have played a pivotal role in shaping the global thermohaline circulation.