A three-dimensional numerical investigation on flow field of lobed mixer which is usually used in modern turbofan engine was carried, on the basement of KIVA program. Standard k- and RNG k- turbulent models were applied for the simulation. According to contrast between experiment results and numerical simulation results, KIVA based on ALE method is able to describe development of shape and value of streamwise vortices and spanwise vortices. Besides, standard k- turbulent model has greater accuracy than RNG k- model in describing maximum value of streamwise vortices and spanwise vortices.