The invention provides a resin-based rain board and a manufacturing method of the resin-based rain board. According to the structure of the rain board, the rain board is formed by arranging hollow semispherical protrusions on the upper surface of a rain board body at intervals; according to the structure of a fastening board, the fastening board is formed in the mode that the two ends of a planar locking board are respectively provided with a half snap ring, and the fastening board is used for connecting and fixing two adjacent rain boards. The manufacturing method comprises the steps of batching of resin-based raw materials, pultrusion of the rain board and field assembly and construction of the rain board. According to the resin-based rain board and the manufacturing method of the resin-based rain board, the resin-based materials subjected to batching are used as the raw materials, and the rain board is subjected to pultrusion and installed and constructed on occasions needing to shelter from rain. The resin-based rain board has the advantages of corrosion resistance, rain and snow prevention, high strength, good structural performance, mechanized production and easy construction, and is suitable for being used as rain boards produced and constructed for the electric power and building fields.