The ideal site should be superficial, easy to reach, easy to puncture, with more collateral circulation on the body surface, and far from veins and nerves. The radial, brachial, femoral, and dorsalis pedis arteries are usually chosen, and the scalp artery can also be chosen for infants and children. The radial artery is more ideal, but more sensitive to pain and less successful for patients with circulatory failure; the femoral artery is thicker and more suitable for patients with circulatory failure and for children. The method of blood collection: 1. Select the appropriate artery, first the radial artery, followed by the femoral, brachial, and dorsalis pedis arteries; the carotid artery is not recommended. 2. Assess the site of the puncture for ulceration, redness, and swelling. 3. 4, the amount of blood drawn is generally in 1-2ml. 5, if there are air bubbles in the syringe after the blood is drawn, it should be promptly eliminated, and the needle should be closed with a rubber plug in time to properly mix evenly. 6, sent for examination.