Blood sampling is a routine operation of clinical blood test, blood sampling in the vein blood collection, general pain is basically able to tolerate, will produce a slight pain, but do not be overly nervous, relax, so as not to produce a sense of fear, to maintain a calm state of mind, so that the pain may be gradually reduced, too much nervousness will produce significant pain, and even the phenomenon of fainting needle. But clinically there is a way of blood collection, such as arterial blood collection, this situation may be relatively more serious degree and nature of pain, arterial blood collection is located in most of the femoral artery, radial artery and other deep arteries, so that the surface of the body’s nerves and sensory sensitivity, the pain may be slightly aggravated by entering the needle. But as long as you relax your mind and face the situation bravely, blood sampling is generally tolerable and will not cause too serious complications.