Abstract: Provided is a constructive light weight insulation block and construction method thereof, and more particularly, to a constructive light weight insulation block on that finishes interior and exterior walls of a building by adding a finishing material to a block main body including light weight bubbling synthetic resin, thereby reducing material costs, simplifying a block building process. The constructive light weight heat insulation block that is stacked in interior and exterior walls of a building is formed of a bubbling synthetic resin, and comprises a coupling projection formed on the top surface thereof so that a recess is not generated when the constructive light weight heat insulation block is stacked, a coupling groove formed on the bottom surface thereof and corresponding to the coupling projection, and a projection portion and a groove portion formed in the front and rear surfaces thereof.