The invention provides a linear cutting machine for a foam concrete heat preservation board. The liner cutting machine comprises a rack. The rack is provided with a material conveying rail. The rack is sequentially provided with a peeling mechanism, an excess material removal mechanism, a transverse cut-off block mechanism and a plurality of cutting mechanisms in the material conveying direction of the material conveying rail. The material conveying rail comprises a conveying rail body, a movable material conveying rail body and a fixed material conveying rail body. The conveying rail body, the movable material conveying rail body and the fixed material conveying rail body are arranged at the same height in a linear mode. The conveying rail body is provided with four first material push rods matched with the end faces of materials to be cut, and the four first material push rods are arranged at equal intervals. By means of the linear cutting machine, the peeling mechanism, the excess material removal mechanism, the transverse cut-off block mechanism and the cutting mechanisms are arranged in the linear mode, materials to be cut can be cut into a plurality of materials of the required sizes, 90-degree turning is not needed, the automation degree is high, the structure is compact, the occupied area is small, and economy is good; all the mechanisms operate in an intermittent mode, and the energy utilization rate is high.