The invention relates to a solid-liquid separation composite filter board and a preparation method thereof; the filter board is made from a separation membrane material, a matrix material and a shrinkage material; an upper separation membrane and a lower separation membrane are respectively composited on the outer surface of each of the upper matrix and lower matrix of the filter board, a liquid support channel is constructed between the upper matrix and the lower matrix, the separation membrane is formed by adding a nucleating agent and an active agent in the matrix material, and the shrinkage material is embedded in the separation membrane; and the matrix material comprises a polyolefin high-polymer material, a zeolites inorganic material, a hydrophilic agent, a coupling agent, a binder, an anticrustator and a dispersing agent. The filter board separation membrane is in composite molding with the matrix at one step; an antiscaling membrane is covered on the surface of granule materials of the matrix and used for the solid-liquid separation of the slurry or liquid, the through hole rate is high and the antiscaling function is good; the match of elasticity, strength and flexibility is proper, the yield of a filter cake is high, the weight of the filter board is light and the service life is long; and the filter board is in a hollow structure and has the advantages of simplicity and convenience in manufacturing process and convenience for mounting.