Engineering vehicle, swing landing leg and lock mechanism of swing landing leg

The utility model discloses a lock mechanism in which a swing landing leg is located at a folding position. The swing landing leg comprises a swing landing leg box and a telescopic supporting leg, wherein the swing landing leg box is pivoted on a car frame, the telescopic supporting leg is arranged in the swing landing leg box, the lock mechanism comprises a locking arm and an elastic reset component, wherein the locking arm is hinged on the swing landing leg box, and the elastic reset component of the locking arm is arranged on the swing landing leg box; and the locking arm is matched with the telescopic supporting leg in a locking way when the swing landing leg is positioned at the folding position. The lock mechanism of the swing landing leg has a simple structure, can work reliably and can complete the protection to the car body automatically.