This paper develops a mathematical economic optimization for urea solution tie-in system in the urea fertilizer plant. The urea solution tie-in system can be used as an effective strategy to increase the urea production and the company revenue as well. The relevant data for the model are obtained from Pupuk Kaltim Fertilizer Company in Indonesia. The mathematical formulation of the model is solved using the General Algebraic Modeling System (GAMS) software. A sensitivity analysis has also been conducted on the optimal solutions of the model. It is concluded that, with the present model, decisions can be made with different strategies and their influence on company revenue. Furthermore, this model will be highly useful for corporate decision making to achieve a maximum profit while meeting certain production targets.