The invention discloses an outdoor mechanical running machine with a speed constraining function. The outdoor mechanical running machine comprises a base, an armrest and running rollers. Two deceleration wheels are respectively arranged at two axial ends of each running roller, grooves are formed in the deceleration wheels in the diameter directions of the deceleration wheels, springs with pre-tightening force are arranged in the grooves, one end of each spring is fixed into the corresponding groove, a check block is connected onto the other end of each spring and can be contracted in the corresponding groove by the aid of the pre-tightening force of the spring, projection of each check block on a movable cover plate is exactly positioned in an antislip barrel when the check block is positioned at a vertical location, and the speeds of the running machine can be constrained under the matching effects of the check blocks and the antislip barrels. The outdoor mechanical running machine has the advantages that the check blocks are matched with the antislip barrels and can be contracted in the deceleration wheels by the aid of the springs, and accordingly accidents caused by excessively high speeds of the outdoor mechanical running machine can be prevented.