The invention relates to a bait casting machine for net cage aquaculture. The bait casting machine for net cage aquaculture comprises a feed box, a buoyancy mechanism, a bait casting disc, a bait casting motor, a time relay and a frequency conversion controller; a conical flow guide platform bulging outward is arranged in the center of the bottom face of the feed box, and a flow guide plate which is correspondingly inclined is arranged at the periphery of the bottom face of the feed box; multiple arc-shaped discharge holes are evenly formed in an annular area between the flow guide plate and the flow guide platform; the bait casting disc is fixedly arranged below the discharge holes, and bait evenly falls onto the bait casting disc in multiple directions through the discharge holes; the bait casting disc is driven by the bait casting motor to rotate, and the bait falling on the bait casting disc is cast into a surrounding water body; the frequency conversion controller of the bait casting motor controls the rotating speed, thereby the casting distance is controlled, and the time relay controls starting and the duration time of the bait casting motor; the distance between each discharge hole and the upper end of a corresponding blade of the bait casting disc is 5-40 mm, when the bait casting disc does not rotate, the bait is warded off by the bait casting disc, no bait is dropped out of the feed box, and when the bait casting disc rotates, the bait is dropped out of the feed box continuously.