The invention discloses a low energy consumption vacuum freeze-drying method capable of recovering and utilizing energy for sludge. The method disclosed by the invention mainly comprises a freezing chamber heat recovery process, a vacuum chamber heat recovery process and a heat source compensatory process for heat shortage part of the vacuum chamber. The low energy consumption vacuum freeze-drying method effectively recovers and utilizes the heat of transformation of moisture in sludge to be dried changed from a liquid state to a solid state, simultaneously recovers and utilizes the heat of the sludge transformed from normal temperature to low temperature, and extracts and utilizes the heat of high-temperature air and high-temperature water in the vacuum drying chamber through a vacuum pump, therefore, the thermal energy consumption in the sludge drying process is greatly saved, energy consumption in the sludge drying process is effectively reduced, and the operating cost is reduced.