The invention relates to a making method for a self-heat preservation lightweight brick. The method comprises the technological steps of: 1) crushing weeds by a crusher; 2) adding crushed grass powder into sludge, mixing and stirring them, then conducting standing; 3) making the mixture into green bricks of various shapes and sizes, and performing airing or drying; and 4) sending the green bricks into a kiln to undergo baking, thus finally forming the self-heat preservation lightweight brick. The making method for the self-heat preservation lightweight brick provided by the invention has the advantages of simple process, low cost, full use of waste materials, environmental pollution reduction and the like. And the prepared self-heat preservation lightweight brick has micropores inside, good thermal insulation performance, and light weight.