The key to the application of reverse osmosis technology is the performance of the reverse osmosis membrane. A reverse osmosis membrane is a semipermeable membrane that allows only water molecules to pass without allowing solute to pass through. Reverse osmosis technology in addition to the application of reverse osmosis and reverse osmosis principle, but also the use of the choice of membrane adsorption and screening mechanism for organic matter. Most of the pore size of the reverse osmosis membrane is less than or equal to 10 × 10-10 m, and the separation object is the organic matter in the solution with ion concentration and molecular weight of several hundred. It can filter out a variety of bacteria, such as one of the smallest bacteria Pseudomonas aeruginosa (3000 × 10-10m), but also filter out a variety of viruses, such as influenza virus (800 × 10-10m), meningitis virus (200 × 10-10m), but also filter the pyrogen (10 ~ 500 × 10-10m). This is a matter of great concern to pharmaceutical water.