The invention provides a biochar grassed slope structure for a coastal reclamation district channel. The biochar grassed slope structure is composed of a turf protection layer, a biochar soil recovery layer, a straw water guide layer and a crushed stone water draining body from top to bottom. The turf protection layer is fixed through cross-shaped wooden piles. The biochar soil recovery layer is formed by mixing biochar, flue gas desulfurization gypsum and local topsoil, and a good substrate is provided for the growth of turf. The straw water guide layer is manufactured by crushed straw with different lengths, and the lengths of the straw are gradually reduced from top to bottom according to the structure of an inverted filter layer. The crushed stone water draining body is arranged at a slope bottom, residual water collected in the straw water guide layer is removed timely. On one hand, the good carbon collecting function of the biochar can be utilized, the soil salinity and alkalinity of a reclamation district is improved, and sufficient nutrition is provided for the growth of the turf, and a slope surface is protected better by the turf. On the other hand, the water guide layer made of the straw prevents salt from accumulating in deep soil, seepage deformation is avoided through the structure of the inverter filter layer, a side slope is protected, and the overall structural performance and stability of the side slope are effectively enhanced.