A buckle assembly for connecting safety belts according to one embodiment of the present invention is provided. The buckle assembly includes a buckle body including two side openings; a release button disposed in the buckle body including an engaging portion; two shoulder-strap buckles each having an opening to allow the waist-strap buckles passing through; and two waist-strap buckles each having a prong portion; wherein each of the shoulder-strap buckles is respectively positioned between each of the waist-strap buckles and the buckle body and incapable of departing from the buckle body freely when the prong portion of the waist-strap buckle is received in each of the side openings of the buckle body and engaged with the engaging portion of the release button; and the shoulder-strap buckles are departed from the buckle body together with the waist-strap buckles when the release button is actuated.