The invention discloses a preparation method for a heat-insulating refractory brick. The preparation method comprises the steps that a high-temperature foaming agent is added into a base material, mixed grindingis conducted till passing a 250-mesh standard screen, and a batch is obtained, wherein the high-temperature foaming agent is two or more of CaCO3, SiC, CaSO4 and BaCO3; the batch is laid and stacked in a mold, put into a high-temperature furnace, heated up to 1000 DEG C at 5-10 DEG C/min and then heated up to 1300 DEG C-1450 DEG C at 2-5 DEG C/min, and heat preservation is conducted for 1-2 h; and the treated batch is cooled to 900 DEG C-1000 DEG C at 5-7 DEG C/min, subjected to heat preservation for 2-3.5 h at the temperature of 900 DEG C-1000 DEG C, then cooled to 500 DEG C at 1-2 DEG C/min and cooled to be lower than 50 DEG C at 2-4 DEG C/min finally, and the mold is dismantled, so that the heat-insulating refractory brick is obtained. By means of a segmented control cooling method, the internal temperature of the prepared heat-insulating refractory brick is equally distributed, the temperature stress is small, the finished product yield is larger than 85%, and heat preservation is conducted at the temperature of 900 DEG C-1000 DEG C, so that recrystallization of a glass body in the material is facilitated, the crystalline phase content in the product is larger than 80%, and the compressive strength and the refractoriness of the material are significantly improved.