The invention provides a pen sleeve and a use method thereof. The pen sleeve involves a pen body, a pen sleeve pipe, an unsealing leakage-proof mechanism and a sealing cover operating mechanism; a metal pen point is fixedly installed at the top of the pen body, the basic structure of the metal pen point comprises a pen point middle seam, and a pen point air hole and a pen tongue, and an infusion channel is formed in the pen body; and one end of the liquid conveying channel is sleeved with a water absorption ink bag, the water absorption ink bag is located in the pen body, and the unsealing leakage-proof mechanism is arranged on the pen sleeve pipe. The invention relates to the field of stationery. According to the pen sleeve and the using method thereof, through the arrangement of a hollowrotary knob, on one hand, a communicating hole can be covered to avoid influence on attractiveness, and on the other hand, the sealing cover body can be rotated through the hollow rotary knob to facilitate connection and separation of the sealing cover body and the pen sleeve pipe, so that the problems of easy drying of pen point and infusion channels thereof are effectively solved, and the problem that for an existing solution, the pen is inconvenient to use, or the infusion channel and the pen point can not be effectively moistened can also be solved.