The invention provides a river channel type reservoir algae control device and method. The river channel type reservoir algae control device comprises a water-proof curtain, the bottom of the water-proof curtain is connected with fixed piers through a plurality of connecting strands, the fixed piers sink to the bottom of water, the top of the water-proof curtain is connected with buoys, and the buoys expand the water-proof curtain and enable the water-proof curtain to be submerged below the surface of the water. The water-proof curtain is made of impervious geotextile and adopts a rectangularplanar structure with the length of 50-150m, the height of 3-15m and the thickness of 0.001-0.01m. The river channel type reservoir algae control method belongs to a surface flow field control methodand is applicable to river channels and reservoirs with certain water depths and slow water flow, a rectification waterpower controlling algae control device has no restriction on the river width, buta small river width is more conducive to the deployment and the operation of the rectification curtain and the cost saving.