The invention discloses a rotary slide block device and a plastic mould applying the rotary slide block device. The rotary slide block device comprises a slide block, wherein the front end of the slide block is provided with a moulding surface, and the upper part and the lower part at the back end of the slide block are provided with hinge holes or hinge shafts of which the central axial lines are parallel to the plane of a mould respectively. The slide block is hinged on a moulding plate on one side of the mould through one hinge hole or hinge shaft, and is hinged on a driving shaft of a slide block driving device through another hinge hole or hinge shaft, wherein the slide block driving device is arranged on the moulding plate of the hinged slide block, and a driving shaft of the slide block driving device performs reciprocating movement along the mould opening direction. Under the same condition, the rotary slide block device can reduce the size of a mould blank relative to a slide block device which moves along a straight line; and at the same time, the mould opening time can be flexibly controlled, namely the mould can be driven to open by the slide block driving device during mould opening or after the mould opening. The plastic mould applying the rotary slide block device can effectively prevent a product from destroying by pulling or dragging during the mould opening.