The invention relates to a method for preparing insulated energy-saving mortar containing phase-change materials, comprising the following steps that: (1) at a temperature of between 30 and 130 DEG C and the vacuum degree is between 0.03 and 0.09, 80 to 500 kg of ceramsite and 0.8 to 2.5 kg of polypropylene hollow fibers are immersed in a phase-change material solution and treated for 5 to 120 minutes, so that the phase-change material solution permeates into holes of the ceramsite and cavities of the polypropylene hollow fibers; (2)the obtained ceramsite and polypropylene hollow fibers, together with 100 to 300 kg of cement and 50 to 200 kg of vitrified micro bubbles, are mixed for 3 to 5 minutes in the condition that the cement water factor is controlled between 0.4 and 0.6. The method is easy and convenient to implement and has low requirement on equipment; and the obtained mortar has good insulated energy-saving effect and can be widely applied in the aspect of heat-insulation of walls in the building field.