NOVELTY - Continuously producing p-nitroaniline, involves: under pressurized condition, forming 30-44% ammonia water; performing ammonolysis at high pressure in pressure vessel having greater than or equal to 2 vessels in series, where in each vessel ammonia water is added and is subjected to 160-180 degrees C and pressure of 4-8 MPa; to ammonia solution in first vessel continuously inputting nitro-benzene to react, where after reaction gaseous ammonia is released and is recovered through relief, and outputting product from end of vessel through continuous separation and water washing to obtain p-nitroaniline and liquor.    USE - For continuously producing p-nitroaniline (claimed), useful as dye intermediate for synthesizing direct lightfast black G, direct green B, BE, 2B-2N, and NB, black green dye, direct grey D, and acid black 10B, as farm chemical, to synthesize bismuth nitrate, as anti-aging agent, and as raw material for light stabilizer and developing agent.    ADVANTAGE - The method for continuous production of p-nitroaniline uses low temperature and low pressure reaction conditions, uses low concentration of ammonia water that is less corrosive to equipment, thus reaction conditions are safe, allows large scale preparation of p-nitroaniline, results in improved product quality, and is low cost. The recycling of ammonia mother liquor recycles ammonia in whole process, and is more environment friendly.    DETAILED DESCRIPTION - Method for continuous production of p-nitroaniline, involves: under pressurized condition, mixing dilute ammonia water and liquid ammonia to prepare 30-44% ammonia water; performing ammonolysis under high pressure in pressure vessel having greater than or equal to 2 vessels in series, where in each vessel having high-pressure obtained, ammonia water is added and is subjected to 160-180 degrees C and pressure of 4-8 MPa; to ammonia solution in first high-pressure vessel continuously inputting nitro-benzene to react with ammonia water subjected to ammonolysis reaction, where after material reaction gaseous ammonia is released and is recovered through relief, and outputting product from end of high-pressure vessel through continuous separation and water washing to obtain p-nitroaniline and liquor.