A monotrack embedded hinge automatic door-closing mechanism, comprising a door mounting block configured to be mounted on a rotating door and a cabinet mounting plate configured to be mounted on a cabinet matched with the door, wherein the cabinet mounting plate drives the door mounting block to rotate through a horizontally rotating connecting rod mechanism, a single guide track mechanism configured to guide the door mounting block to contract and change a track is provided between the door mounting block and the cabinet mounting plate, wherein the single guide track mechanism comprises a chute rod vertically fixed on the cabinet mounting plate and a guide chute formed in the door mounting block, and wherein the chute rod vertically upwards penetrates through the guide chute and guides a rotating action of the door mounting block along an interior of the guide chute; wherein the connecting rod mechanism comprises a limiting fixed shaft, a limiting connecting rod and a limiting swing shaft, the limiting fixed shaft is rotatably fixed on a panel of the cabinet mounting plate, the limiting connecting rod is horizontally fixed on a top rod wall of the limiting fixed shaft, the limiting swing shaft is vertically fixed at a top of an outer end of the limiting connecting rod, and a top end of the limiting swing shaft is rotatably fixed in a middle of the door mounting block; characterised in that a spring mounting rod is fixed on the door mounting block, an angle retaining block is rotatably fixed on a panel of the door mounting block on a side opposite to the spring mounting rod, an outer wall of the angle retaining block is slidably connected with a top end of the chute rod, and when the chute rod is moved in the guide chute, the top end of the chute rod drives the angle retaining block to rotate; in that a reset spring is mounted between the angle retaining block and the spring mounting rod, and when the door mounting block is rotated to a side of attachment to the cabinet mounting plate and is in a closed state, the reset spring is in a stretched state, the angle retaining block tightly abuts against the chute rod without displacement, and when the door mounting block is moved to a fully opened position, the angle retaining block is overturned to the top end of the chute rod and kept at the top end, and in the overturning process of the angle retaining block, the reset spring provides a closing rotating force for the door mounting block, and when the top end of the chute rod is fixed at a bottom of the angle retaining block, the reset spring does not provide the closing rotating force for the door mounting block. wherein the cabinet mounting plate drives the door mounting block to rotate through a horizontally rotating connecting rod mechanism, a single guide track mechanism configured to guide the door mounting block to contract and change a track is provided between the door mounting block and the cabinet mounting plate, wherein the single guide track mechanism comprises a chute rod vertically fixed on the cabinet mounting plate and a guide chute formed in the door mounting block, and wherein the chute rod vertically upwards penetrates through the guide chute and guides a rotating action of the door mounting block along an interior of the guide chute; wherein the connecting rod mechanism comprises a limiting fixed shaft, a limiting connecting rod and a limiting swing shaft, the limiting fixed shaft is rotatably fixed on a panel of the cabinet mounting plate, the limiting connecting rod is horizontally fixed on a top rod wall of the limiting fixed shaft, the limiting swing shaft is vertically fixed at a top of an outer end of the limiting connecting rod, and a top end of the limiting swing shaft is rotatably fixed in a middle of the door mounting block; characterised in that a spring mounting rod is fixed on the door mounting block, an angle retaining block is rotatably fixed on a panel of the door mounting block on a side opposite to the spring mounting rod, an outer wall of the angle retaining block is slidably connected with a top end of the chute rod, and when the chute rod is moved in the guide chute, the top end of the chute rod drives the angle retaining block to rotate; in that a reset spring is mounted between the angle retaining block and the spring mounting rod, and when the door mounting block is rotated to a side of attachment to the cabinet mounting plate and is in a closed state, the reset spring is in a stretched state, the angle retaining block tightly abuts against the chute rod without displacement, and when the door mounting block is moved to a fully opened position, the angle retaining block is overturned to the top end of the chute rod and kept at the top end, and in the overturning process of the angle retaining block, the reset spring provides a closing rotating force for the door mounting block, and when the top end of the chute rod is fixed at a bottom of the angle retaining block, the reset spring does not provide the closing rotating force for the door mounting block.