The utility model discloses a large tracts of land light fire compartment wall, it includes: vertical braces spare, it is located between the adjacent vertical I -steel, one end and top I -steel fixed connection, the other end and ground fixed connection, horizontal support piece, one end is connected with vertical I -steel, and the other end is connected with adjacent vertical I -steel, vertical skeleton is fixed on horizontal support piece, horizontal skeleton is fixed on vertical braces spare, a fire -proof plate layer fixes in vertical skeleton one side with horizontal skeleton, the 2nd fire -proof plate layer fixes at the opposite side of vertical skeleton with horizontal skeleton, pack between a fire -proof plate layer and the 2nd fire -proof plate layer on the rock wool layer. The utility model discloses fire compartment wall has increased support piece between original building structure top I -steel and vertical I -steel, make vertical skeleton and horizontal skeleton can install on the building structure of large tracts of land to can keep fire compartment wall's intensity, prevent owing to crooked, the fracture of ambassador's skeleton is crossed to fire -proof plate layer, rock wool layer weight.