The effect of a heat preservation furnace is particularly important in a low-pressure casting machine. An existing heat preservation furnace is not suitable for all low-pressure casting machines, and some low-pressure casting machines needs specially designed low-pressure casting heat preservation furnaces so as to facilitate workpiece machining. For solving the problem, the invention provides the low-pressure casting heat preservation furnace. After the low-pressure casting heat preservation furnace is adopted, a silicon carbide rod is utilized to perform heating, a heat preservation material in a heat preservation cavity is utilized to perform heat preservation, and accordingly the heat preservation effect is achieved.