A nitrogen oxide absorption slurry and its preparation and use method for the removal of nitric oxide in gas streams, belonging to the technical field of air pollution control and related environmental protection, is characterized in that the absorption slurry contains one or more compounds of anhydrous ferric chloride, ferric chloride monohydrate, ferric chloride dihydrate and the complex of ferric chloride and chloride ions. The absorption slurry reacts with the nitric oxide in gas stream at a certain temperature, so that the nitric oxide in the gas stream is absorbed by the slurry, thereby achieving the purpose of gas purification. And the absorbent can be recycled after regeneration.