The invention discloses an engine cold-start preheating device. A heat storing heat exchanger (3) is in a parallel connection with an exhaust pipe (2) of an engine (1), the heat storing heat exchanger (3) is used for storing exhaust air waste heat of the engine (1), the heat storing heat exchanger (3) is in a columnar structure, a plurality of heat storing units are distributed in the heat storing heat exchanger (3), each heat storing unit is a concentric casing pipe (7) which comprises an inner pipe and an outer pipe, a phase change thermal storage material (8) is encapsulated in annular space between the inner pipe and the outer pipe, two ends of the inner pipe are welded on two flow guide plates (9) respectively, a hollow cavity for enabling cooling water of the engine (1) to flow through is formed by the two flow guide plates (9) and inner walls of the heat storing heat exchanger (3), and the inner walls of the heat storing heat exchanger (3) are located between the two flow guide plates (9). The engine cold-start preheating device has the advantages of being low in costs, small in size, efficient, energy-saving and convenient to popularize and use in a wide range.