The invention discloses a 
system for producing 
ammonia gas by hydrolyzing a 
urea solution. The 
system comprises a hydrolyzer, a hydrolyzer 
thermometer T1, a hydrolyzer pressure 
transmitter P, a hydrolyzer liquidometer L, a 
urea solution regulating valve A1, a hydrophobic 
heat exchanger, a steam regulating valve A2, a hydrolyzing gas outlet regulating valve A3, a steam 
heat exchanger, a hydrolyzing gas outlet 
thermometer T2, a hydrolyzing gas outlet flowmeter F, a steam hydrophobic valve and a 
hydrolysis system control module, wherein the hydrolyzer is provided with seven ports respectively connected with the components above; the 
hydrolysis system control module is respectively connected with the hydrolyzer 
thermometer T1, the hydrolyzer pressure 
transmitter P, the hydrolyzer liquidometer L, the 
urea solution regulating valve A1, the steam regulating valve A2, the hydrolyzing gas outlet regulating valve A3, the hydrolyzing gas outlet thermometer T2 and the hydrolyzing gas outlet flowmeter F through cables. The invention also discloses a control method for producing 
ammonia gas by hydrolyzing the urea solution, which is implemented through six steps. The system and control method disclosed by the invention are simple and reliable, and easy to control. Steam is taken as a heat source of a 
hydrolysis system, so that the operation cost and the 
energy consumption are reduced.