A multi-point seat belt assembly (1A, 1D), comprising: a buckle assembly comprising a buckle member; and a tongue member detachably inserted into the buckle member; two webbing-locking mechanisms mounted on the buckle assembly, and each webbing-locking mechanism comprising a connecting member and a movable member mounted movably on the connecting member, wherein the connecting members of the two webbing-locking mechanisms are connected respectively with the buckle member and the tongue member; two main webbings mounted respectively through the webbing-locking mechanisms and each main webbing having two ends; and at least one retractor, wherein one end of each main webbing is connected with one of the at least one retractor, and the other end of each main webbing is adapted to be connected with a vehicle seat, wherein the connecting member of each webbing-locking mechanism has a through hole defined through the connecting member, a front side, and a rear side opposite the front side; and the movable member of each webbing-locking mechanism comprises a front portion located at the front side of the connecting member of the webbing-locking mechanism and having a limiting protrusion formed on and protruding from the front portion and extending slidably in the through hole in the connecting member; and a rear portion located at the rear side of the connecting member of the webbing-locking mechanism, wherein the front portion and the rear portion have a height difference between each other; wherein each main webbing passes through the through hole in the connecting member of a corresponding one of the webbing-locking mechanisms via a space defined between the connecting member and a front end of the front portion of the movable member of the corresponding webbing-locking mechanism and passes a bottom of the rear portion of the movable member of the corresponding webbing-locking mechanism. a buckle assembly comprising a buckle member; and a tongue member detachably inserted into the buckle member; a buckle member; and a tongue member detachably inserted into the buckle member; two webbing-locking mechanisms mounted on the buckle assembly, and each webbing-locking mechanism comprising a connecting member and a movable member mounted movably on the connecting member, wherein the connecting members of the two webbing-locking mechanisms are connected respectively with the buckle member and the tongue member; two main webbings mounted respectively through the webbing-locking mechanisms and each main webbing having two ends; and at least one retractor, wherein one end of each main webbing is connected with one of the at least one retractor, and the other end of each main webbing is adapted to be connected with a vehicle seat, wherein the connecting member of each webbing-locking mechanism has a through hole defined through the connecting member, a front side, and a rear side opposite the front side; and the movable member of each webbing-locking mechanism comprises a front portion located at the front side of the connecting member of the webbing-locking mechanism and having a limiting protrusion formed on and protruding from the front portion and extending slidably in the through hole in the connecting member; and a rear portion located at the rear side of the connecting member of the webbing-locking mechanism, wherein the front portion and the rear portion have a height difference between each other; a front portion located at the front side of the connecting member of the webbing-locking mechanism and having a limiting protrusion formed on and protruding from the front portion and extending slidably in the through hole in the connecting member; and a rear portion located at the rear side of the connecting member of the webbing-locking mechanism, wherein the front portion and the rear portion have a height difference between each other; wherein each main webbing passes through the through hole in the connecting member of a corresponding one of the webbing-locking mechanisms via a space defined between the connecting member and a front end of the front portion of the movable member of the corresponding webbing-locking mechanism and passes a bottom of the rear portion of the movable member of the corresponding webbing-locking mechanism.