Green process for preparing orthoformate

The invention provides a green process for preparing orthoformate. A hydrogen chloride alcohol solution is prepared from a byproduct hydrogen chloride tail gas of the chlorine-related synthesis industry and then is slowly added into a reaction system, so that loss caused by escape of hydrocyanic acid is reduced, the yield is increased, great equipment corrosion caused by the byproduct hydrochloric acid prepared by the companies is avoided, the economic additional value of the byproduct hydrogen chloride is greatly increased, three wastes are avoided, the byproduct only comprises ammonium chloride, resources are reasonably utilized, and the green process for preparing the orthoformate is an environment-friendly production process and has a good social benefit.