The invention discloses a shell-and-tube multifunctional heat exchanger. The shell-and-tube multifunctional heat exchanger is characterized in that tube plates are welded to two ends of a horizontal shell tube arranged in the horizontal direction, head plates are fastened outside the tube plates, the lower portion of the inside of the horizontal shell tube is a liquid storage area, the middle of the horizontal shell tube is provided with a heat exchange tube bundle, the upper portion of the horizontal shell tube is provided with a homogenizing plate provided with through holes, first coolant flows through the tube side to form an evaporating side of a steam compression refrigerating loop, and second coolant flows through the shell side to be cooled or condensed in the shell side and is used to supplement cold of a natural cold source required for air-cooling heat exchanging. The shell-and-tube multifunctional heat exchanger is suitable for dual-cold source refrigerating air-conditioning systems, such as heat tube/steam compression hybrid refrigerating systems and air-cooling/steam compression hybrid refrigerating systems, has the functions of a condensation evaporator or dry evaporator and a liquid storage, and has the advantages of compact structure, pressure resistance and good tightness.