The invention relates to a water tank type seawater desalination and vegetable planting support ship which comprises a hull. A hull deck is fixedly arranged in the middle of the hull; partitions are fixedly arranged between the hull deck and the hull to form a water concentrating bin, an evaporating bin and a rainwater bin; a vegetable planting chamber is fixed right above the rainwater bin; a guard wall, a downpipe, a root-proof layer, a water outlet pipe, a rainwater hole and an electrical appliance control system are arranged at the upper right part of the deck; a water storage and drainage layer, a filtering layer and a planting layer are sequentially arranged on the root-proof layer in the guard wall; a water pump is arranged in the rainwater bin; the water outlet pipe of the water pump is communicated with a sprinkler pipe via a partition; the rainwater hole is formed in the top of the rainwater bin, on the hull deck and outside the guard wall in a separation manner; a light transmitting plate is arranged at the top of the vegetable planting chamber; seawater enters a condensing pipe after being filtered by a filter 2, and then is pressed into a lens water tank by the water pump to be heated by solar energy, sunlight is focused into a heat concentrating pipe after passing through the lens water tank, seawater flowing out of the lens water tank is further heated in the heat concentrating pipe 25, the heated seawater flows into a spraying pipe, and mist is sprayed out via a spray nozzle, is drawn into a water concentrating chamber 2 via an induced draft fan and is condensed into fresh water by the condensing pipe. The water tank type seawater desalination and vegetable planting support ship can be fixed on an island or move along with a ship, can simultaneously carry out seawater desalination and vegetable planting, and is low in cost and good in effect.