The invention discloses an antifouling spraying device based on composite material surface treatment. The device comprises a liquid storage tank, wherein a partition is arranged between the upper andlower surfaces inside the liquid storage tank and divides the liquid storage tank into a water storage chamber and a liquid storage chamber, a delivery pump is arranged in each of the water storage chamber and the liquid storage chamber, a water delivery pipe and a liquid delivery pipe are mounted on the two delivery pumps respectively, inserted into a sleeve and arranged together in a sleeving manner by the sleeve. The antifouling spraying device based on composite material surface treatment is additionally provided with an antifouling cover, so that objects not needing spraying can be prevented from being sprayed in the spraying process, the trouble of removing residual paint by manually cleaning the objects in the subsequent process is avoided, and the device is time-saving, labor-saving, good in antifouling performance and practicability.