Abstract: Temporal and spatial distribution of urea with impacting factors was studied based on 4 seasonal investigations on the water quality of Xiamen sea area in August and October of 2016, and in January and May of 2017. The results show that the Urea-N concentration in surface water can be ordered in sequence of summer, spring, autumn and winter with average values 3.06±1.09, 2.64±0.82, 2.30±1.43 and 1.67±0.79 μmol/dm³, respectively. The Urea-N concentration in bottom water layer is ordered in sequence of spring, summer, autumn and winter with average values 3.13±0.95, 2.70±1.25, 1.65±0.80 and 1.56±0.88 μmol/dm³, respectively. Higher concentration of UreaN was mostly located in the river mouth, the west waters of Xiamen and Tongan Bay in contrast to the lower concentration in nearby open sea areas. The results of correlation analysis based on spatial and temporal distribution feature of urea and its environmental factors in Xiamen sea area show that the distribution of urea is affected not only by runoff input and sewage discharge, but also by mariculture, marine biological activities and tidal currents. These factors jointly regulate the pattern of spatial and temporal distribution of the urea in the sea. In spring, urea is an important component of the available nitrogen source, especially in Dadeng sea area of Xiamen.