Abstract: Some technical concepts of process conditions for methanolization and methanation purification of ammonia synthesis feed gas are presented. The above purification process could be operated under the pressure of 5.0～30.0 MPa., but methanolization should be operated under a medium or low pressure to save energy. In the second-stage of methanolization, CO+CO2 at the inlet should be 1.8％～2％ and CO+CO2 at the outlet should be 0.1％～0.15％ so that the energy consumption could be the least. Autothermic reaction of methanation could not take place when purifying the synthesis feed gas. By analyzing and assessing three supplemental ways of heating, there are some difficult problems, such as safety concerns of the equipment, inversion of the operation order,etc., when heating unreacted gas in methanation with exit hot gas from ammonia synthesis.