A Cordyceps militaris medium polysaccharide, a method for separating and purifying same, and the use thereof, wherein the polysaccharide comprises the following monosaccharides in mole percentages: 0.11% ribose, 0.11% rhamnose, 0.45% arabinose, 0.13% xylose, 14.50% mannose, 83.96% glucose, and 0.73% galactose. The extraction method does not affect the biological activity of the Cordyceps militaris medium polysaccharide P1; the obtained purified polysaccharide P1 has high purity and stable properties, and has significant effects on resistance to oxidation, lowering uric acid and bacteriostasis, which are beneficial to human metabolism; due to the low cost, the purified polysaccharide P1 can be further used in the development of health products, drugs and cosmetics.