陆桥说（英语：Land bridge）是生物地理学的一种学说，用来解释不同大陆出现相同或类似物种的原因。科学家认为以往各大陆有狭长的地峡（陆桥）相连，使生物能在各大陆互相走动，后来这些地峡慢慢沈到海洋中，才造成今日各大陆的独立。此一学说后被大陆漂移学说推翻。

A land bridge, in biogeography, is an isthmus or wider land connection between otherwise separate areas, over which animals and plants are able to cross and colonise new lands. A land bridge can be created by marine regression, in which sea levels fall, exposing shallow, previously submerged sections of continental shelf; or when new land is created by plate tectonics; or occasionally when the sea floor rises due to post-glacial rebound after an ice age.