Disposable medical bloodletting instrument

The invention discloses a disposable medical bloodletting instrument. A needle head is installed at one end of a needle column, the other end of the needle column is connected with an adjusting knob, and the adjusting knob is provided with a button. The needle head is arranged in a lower needle sleeve, the lower needle sleeve is connected with an upper needle sleeve through a spiral buckle, the upper needle sleeve is provided with an inclined groove and a one-way spiral type dividing rule, and an observation window is further arranged inside the upper needle sleeve. In the disposable medical bloodletting instrument, the stainless steel needle sleeves are selected, the inclined groove pushes the needle head to expand and contract, and the needle head can be pushed forwards by 0.3 mm every time the one-way spiral type dividing rule goes by one scale; the depth of the operating needle head can be controlled according to ages, constitutions, genders and parts of patients, one needle head can be used for only one person, so medical safety is guaranteed, and a route of blood infection is eliminated; in addition, the disposable medical bloodletting instrument is easy and convenient to operate, clear in curative effect, free of toxic and side effects, free of scars, low in price, free of limitations of time and places and easy to apply and popularize in basic level medical and health organizations and rural medical and health organizations.