The urea plant in our company is a large-scale Stamicarbon CO2 stripping urea plant introduced from Netherlands in the early 1970s with the daily and annual production of 1620 mt and 480 kt respectively. Since its commissioning in 1977, the evaporation system has undergone a number of revamps which are mainly focused on the second evaporator section such as adding louvers, adding flushing points, and using a larger booster (702L) etc. In recent years, there is a frequent problem in the first evaporator in that the outlet temperature of urea solution is hard to increase especially at high plant load conditions. So an analysis of this problem is presented here in this paper.