The invention discloses a plate type low-temperature multieffect seawater desalting device and method. The device mainly comprises a metal partition, liquid-absorbing cotton cloth, a vacuum pump, a fresh water residual heat exchanger, a seawater heater, a feedback controller, and a flow control valve. Vapor in two condensation chambers adjacent to an evaporating chamber is condensed to release and transfer potential heat to a seawater falling film on the wall surface of the middle evaporation chamber, the seawater falling film absorbs heat for evaporation, the generated vapor is introduced into the adjacent condensation chamber, the unevaporated seawater is pumped into the next evaporation chamber, the seawater falling film on the wall surface of the evaporation chamber absorbs and evaporates the potential heat released by condensation of steam in the condensation chamber at the left side and the condensation chamber at the right side, and the potential heat is recycled repeatedly in the mode, wherein secondary steam is introduced into the condensation chamber at the right side. According to the plate type low-temperature multieffect seawater desalting device and method, residual heat of a part of fresh water can be recovered; and the device is compact in structure, small in occupied area, not easy to scale, convenient to disassemble and wash and high in quality of producing water.