Insulin pen injection needles need to be changed one at a time and cannot be reused, so as to avoid burrs, bends and barbs in the needles, which can increase the pain of injection and easily form fat pads. In addition, there will be residual insulin crystals in the used needles. Repeated use will cause the needles to become blocked, which will affect the next discharge of the medicinal solution. Repeated use also increases the risk of needle breakage. In order to reduce pain, insulin needles are extremely thin and are produced according to disposable standards. Repeated use can easily break the needle in the body. The broken needle will swim in the body, which is difficult to remove, and it is very harmful.