The invention belongs to the technical field of geotechnical instruments and particularly relates to a horizontal permeameter for geotextile. The horizontal permeameter comprises a permeation measuring device and a gas and water removing device, wherein the gas and water removing device is arranged on the left side of the permeation measuring device, and the permeation measuring device comprises a first-stage support platform, a permeation chamber, an object table, a press block and a support block; the permeation chamber is arranged at the top of the first-stage support platform, an infiltration water container is arranged on the first-stage support platform on the left side of the permeation chamber, an exudation water container is arranged on the first-stage support platform on the right side of the permeation chamber, the object table is arranged at the bottom in the inside the permeation chamber, the press block is arranged above the object table, and an inverted-U-shaped groove allowing the object table to be inserted in is formed in the bottom of the press block. The horizontal permeameter for the geotextile can test the horizontal permeation performance of the geotextile in a laboratory, obtains more accurate and stable test results and has the advantages of being simple in structure and convenient to operate.