Abstarct: Aerated lagoons are inexpensive technologies of wastewater treatment that are mostly used in temperate climate areas as well as cold climate areas if sufficient land is availabel. Surface mechanical aerators are used for better operation of aearted lagoons. Nowadays, in the design of aerated lagoons, parameters such as the geometric shape of the lagoon, the optimal number and power of surface mechanical aerators, the arrangement of aerators and the mixing pattern in the lagoon optimized to achieve maximum oxygen transfer efficiency with technologies such as computational fluid dynamics. This technique can use computer simulation technology to provide three-dimensional models of the flow pattern in the lagoon in different hydrodynamic situations due to the arrangement of surface mechanical aerators as well as the type of aerator blade. The present study has been performed to numerically investigate the flow pattern in a aerated lagoon with a cone shape aeration pattern in turbulent flow regime. Geometry production and evaluation is done in Auto Cad software. A meshless structure method has been used in Icem CFD software to model the flow around the aerator and lagoon. The turbulent flow regime and the Standard K-ε turbulence model are selected for modeling. Three cone shape aerators are designed with different heights, rotation angles, and blade depths. The cone shape aerators were analyzed separately in a lagoon at 80 rpm with Ansys Fluent software. The velocities generated by these three aerators at three different depths of the lagoon were evaluated.