The invention provides a technological method for co-production of ammonium bicarbonate through melamine tail gas and solves the problems that material balance is difficult, gas purification is substandard, the technology fluctuation range is large, and the like in a conventional production technology. The technological method comprises a co-production system formed by an ammonia tank, a main carbonizing tower, an auxiliary carbonizing tower, a bubble column, a thickener, a centrifugal machine and a mother liquor tank. The main carbonizing tower, the auxiliary carbonizing tower and the bubble column are operated, the temperature in the bubble column is kept to be 40-45 DEG C, and the tower boiling times are decreased; and the CO2 content in stronger ammonia water in the main carbonizing tower is controlled to be 120-124 mol / L, the yield of ammonium bicarbonate is determined according to the amount of the CO2, and materials are balanced, so that balance is achieved. According to the technological method, the main carbonizing tower, the auxiliary carbonizing tower and the bubble column are operated, the temperature in the bubble column is kept to be 40-45 DEG C, the yield of ammonium bicarbonate is determined according to the amount of the CO2 at the same time, and materials are balanced, so that balance is achieved. According to the technological method, an expected purpose is achieved, and carbonization process influences are relieved, so that an ammonia synthesis system can operate more stably.