The invention relates to the field of tunnel brick structures used for engineering construction, in particular to a tunnel brick used for engineering construction. A plurality of partition plates arearranged at the upper part of a brick body of the tunnel brick. The partition plates divide the tunnel brick into a plurality of groove structures with the same size. The front wall and the back wallof each groove are symmetrically provided with screw holes which are used for being in threaded connection between the upper and lower tunnel brick structures. A side convex structure is arranged on the left side surface of the brick body. A side concave structure matched with the side convex structure is arranged on the right side surface of the brick body and used for being in sided matching connection between the horizontal adjacent spliced tunnel bricks. The brick body is made of a mixture of fly ash and concrete. The tunnel brick is simple in structure, saving in material and convenient to pile and has good practical value.