The utility model discloses a crankshaft clockwise and anticlockwise rotating device when an engine is judged to stop working. The device comprises a signal panel (1), a No.1 photoelectric sensor (3) and a No. 2 photoelectric sensor (6). The No. 2 photoelectric sensor (6) is arranged right under the signal panel (1) along with the radial direction, a fan-shaped tooth on the signal panel (1) is embedded into a groove at a fork-shaped end of the No. 2 photoelectric sensor (6), the No.1 photoelectric sensor (3) is arranged at the right side of the signal panel (1) along with the radial direction, a fan-shaped tooth on the signal panel (1) is embedded into a groove at a fork-shaped end of the No.1 photoelectric sensor (3), the tooth top surface and the front and rear end surfaces of the fan-shaped tooth on the signal panel (1) is in clearance fit with the inner surfaces of the grooves at the fork-shaped ends of the No.1 photoelectric sensor (3) and the No. 2 photoelectric sensor (6), and an inclined angle alpha between the No.1 photoelectric sensor (3) and the No. 2 photoelectric sensor (6) is equal to 90-1/2*360/2n degrees, wherein n is the tooth number of the signal panel, and n is a positive integer within the range from 12-180.