Anti-loosening connecting fastener

The utility model provides an anti-loosing connecting fastener which comprises a main bolt, a nut matched with the main bolt and a tensioning bolt, a hole is coaxially formed in the main bolt, the tensioning bolt is matched with the hole, a plurality of openings are evenly formed in the bottom of the main bolt around the outer circumference, the openings are communicated with the hole, and the nut is matched with the tensioning bolt. The multiple openings enable the end, away from the main bolt head, of the main bolt rod body to form an expansion cavity. The connecting fastener further comprises a stop cushion arranged between the nut and the expansion cavity. The expansion cavity at the bottom of the main bolt is expanded through the expansion bolt, movement of the nut is limited, and the expansion bolt and the nut are fixed together through the locking cushion, so that the main bolt, the expansion bolt and the nut are fixed together and cannot loosen. 本实用新型提供一种防松动联接紧固件，包括主螺栓、与主螺栓相配合的螺母、涨紧螺栓，所述主螺栓内同轴开设有孔，所述涨