The invention relates to an improvement on the ammonia-nitrogen content of H acid wastewater, in particular to a method for improving the ammonia-nitrogen content of the H acid wastewater. The method comprises steps of denitration, separation of sodium sulfate hydrate serving as a byproduct, reduction and T acid dissociation. According to the method, the treatment of the wastewater in a product preparation process can be improved to protect the environment and reduce pollutant discharge.