The invention relates to a method for extracting cobratide, a medicine used to treat chronic pain, the cobratide extracted by the method and a preparation containing the cobratide. The method for extracting the cobratide comprises the following steps: firstly, a stock solution of snake poison of a cobra is pretreated with ammonium sulphate to remove partial other compositions in the snake poison,is subjected to desalination and concentration through ultrafiltration, dialysis or gel chromatography, and after the concentration, is purified by a cation column, and finally is subject to freeze-drying preservation after the concentration. The cobratide preparation comprises an enteric preparation, a rectal administration preparation, a colon-specific administration preparation and so on. Withcobratide extraction and purification processes provided by the method, the purity of the extracted cobratide is more than 95 percent, and the yield reaches 70 percent; and the method is simple and reliable, and saves cost and time.