Forward osmosis treatment system of saline-alkaline water and treatment method thereof

The invention discloses a forward osmosis treatment system of saline-alkaline water, comprising an exchange tank wherein a frame for mounting a forward osmosis membrane is mounted; two sides of the forward osmosis membrane are used for introducing drawing liquid and raw liquid respectively, the bottom of the exchange tank is connected respectively with a drawing liquid incoming pipe and a raw liquid incoming pipe, the top of the exchange tank is provided with a drawing liquid outgoing pipe and a raw liquid outgoing pipe, the drawing liquid outgoing pipe is connected to a concentration adjusting tank, and the raw liquid outgoing pipe is connected to a raw liquid concentrating and precipitating tank; the exchange tank is internally provided with a plurality of first partitions to the drawing liquid side, the first partitions are provided with first through holes, the exchange tank is internally provided with a plurality of second partitions to the raw liquid side, the second partitions are provided with second