The invention discloses a horizontal filter press. The horizontal filter press comprises a base, two guide rails which are arranged on the base and are parallel to each other, a plurality of mud fixing frames which are arranged on the guide rails in an extending direction of the guide rails, and a driving device for compressing and separating the plurality of mud fixing frames; a concave part is formed at one end of each mud fixing frame; a convex part which is matched with the concave part is formed at the other end of each mud fixing frame; the convex part of one mud fixing frame can extend into the concave part of the adjacent mud fixing frame to form a filter pressing chamber; a material inlet and a water outlet which are communicated with the filter pressing chamber are formed in each mud fixing frame; filtering cloth which is matched with each water outlet is arranged in the corresponding filter pressing chamber. According to the horizontal filter press disclosed by the invention, the convex part of one mud fixing frame can extend into the concave part of the adjacent mud fixing frame to form the filter pressing chamber, and each convex part and the corresponding concave part which form the corresponding filter pressing chamber extrude with each other under the driving of the driving device, so that the extruding force applied to a solid-liquid mixture is greatly increased; solid-liquid separation can be effectively realized; deep dehydration of a material can be realized.