The invention discloses an insulating module of a planted roof, which is an edgeless platform fitting cylinder formed by enclosure of trapezoidal side surfaces and rectangular side surfaces. A plurality of modules are assembled forwardly and reversely paved on the roof; and flowers and grasses are planted in planting soil of holes on the modules so as to form the planted roof. In the insulating module of the planted roof, no-limitation forward-reverse combination tight laying of the roof with any size can be realized, the wet filling operation is reduced, the planting number is increased, the procedures of the system are fewer, the construction is convenient, the construction period can be shortened, the labor intensity can be reduced, the self weight is light, the combination is convenient, the waterproof performance is good, simultaneously the insulation and the heat storage are achieved, the temperature gradient is small, the protection to flowers and grass is good, the greening rate for the environment of a building is increased, the noise pollution is reduced, the oxygen-rich degree is increased and the environmental comfort is high. The insulating module is grade-A fireproof material, and also has the characteristics of light self weight, waterproof and fireproof functions, no limitation of the height and the modeling of the building, easy renovation, good vapor permeability and the like.