Under the current environmental protection situation, comparison on techno-economic analysis of the ammonia production using urea can provide reference and guidance for the coal plant’s transformation project of replacing liquid ammonia with urea. Taking eleven 300MW SCR denitrification reducing agent urea replacing liquid ammonia in 4 power plants as an example, the technical characteristic and material consumptions, investment cost and operation cost were compared on urea pyrolysis with electric heater, urea pyrolysis with gas heat exchanger and urea hydrolysis, the main influence factors and reasons of Urea to replace liquid ammonia transformation project on such unit had been mastered. The results show that the processes of ammonia production by urea pyrolysis and urea hydrolysis were mature and feasible, and both had their advantages and disadvantages.