The invention discloses a low-temperature multi-effect distillation seawater desalting plant, which comprises a steam supply system, a water distribution system, an evaporation plant, a freshwater system and a concentrated water system, wherein the evaporation plant comprises an evaporator, a condenser, a flash tank and a steam pipeline, and the evaporator is a multi-effect evaporator and comprises a barrel, end sockets, flanges and necessary pipelines; the end sockets are connected with the barrel through the flanges to form evaporation rooms, the evaporation rooms are connected with one another through the flanges and the necessary pipelines to form a modular evaporation room; a support frame of the flash tank is arranged at the two sides of the bottom of an evaporator shell, and the flash tank is fixedly arranged on the support frame of the flash tank; the condenser is fixedly arranged on and is communicated with the rear section of the evaporator; and one end of the steam pipeline is communicated with the end socket, and the other end of the steam pipeline is communicated with the condenser through an assembling unit of a steam pipe. The heat is more reasonably transferred, the irreversible loss is reduced to the minimum, the heat utilization rate is improved, the cost is saved, the water producing rate is improved, and the occupied area is small.