Although the urea production technology is mature and already well developed, there are few studies on modelling and simulating the process.There has been some efforts to model and simulate the urea reactor and the synthesis section take into account the biuret formation, nevertheless thermodynamics properties of the components have been estimated in both studies according specific industrial data.The present study proposes to model and simulate the synthesis section of an urea unit. Validation of the model was demonstrated using industrial data. In the last step key variables to evaluate the biuret formation are discussed and analyzed.