The invention discloses a digital measuring device for a heat expansion rate and working quantity of solid-liquid phase transformation materials under normal pressure, which belongs to the physical measuring field. The invention comprises an inner container, an outer container, an air discharging lock, a pressure sensing device, a water level gauge, a water valve, a sampling control unit, a heat electric couple, and an automatic electric heater. The inner container is arranged crosswise inside the outer container, an emulsion film is arranged on one end of the inner container through a compression ring and an O-shaped rubber ring, the inner container is filled fully with measuring working fluid, the outer container is filled fully with water, the rubber ring is expanded out due to an expansion of the working fluid along water temperature rising inside the outer container, and water level inside the water gauge rises. The heat expansion rate and the working quantity of the solid-liquid phase transformation materials under normal pressure can be calculated out according to liquid levels as volume expansion signal, temperature and pressure signal, which provides a convenient and reliable approach for performance measurement of the solid-liquid phase transformation materials. The invention is applicable to materials as n-pentadecane, n-hexadecane, heptadecane, sodium acetate trihydrate, storing thermal paraffin RT 54 which is produced by a German company, and the similar materials.