The invention relates to a double-pipe heat exchanger with deflection fins deviating and spreading at both sides in the technical field of machines. The heat exchanger comprises an outer pipe, an inner pipe and a plurality of fins, wherein the outer pipe is sleeved to the inner pipe; the fins are arranged in an annular space between the outer pipe and the inner pipe and comprise supporting pieces and deflection fins; both ends of the supporting pieces are respectively connected with the inner wall of the outer pipe and the outer wall of the inner pipe; the supporting pieces are arranged along the radial direction of the inner wall of the outer pipe; and one ends of the deflection fins are connected with the outer wall of the inner pipe, while other ends are deviated towards both sides by forming angles of 5-20 degrees along the radial direction of the outer pipe. At the same time of being used as supports of the inner pipe and the outer pipe, the fins also increase the heat exchange area of the inner pipe, thereby not only reducing the heat transfer of the fins to the outer pipe, but also ensuring that media flowing though can reduce or destroy a boundary layer and increase perturbance so as to improve the heat exchange efficiency. The whole device has large heat exchange area, small volume, simple structure and less material consumption.