Abstract: The three-dimensional optional quasi-normal intersection surface method for calculation of interior flow of impeller mechanism is slightly modified,then used to calculate the interior flow of stirring impeller.The calculated three-dimensional velocity distribution of impeller discharge flow basicly meets the experiment results.The calculated results show that dimensionless velocity disctribution of impeller discharge flow at different rotational speeds coincides with each other, and impeller diameter,blade laying angle ,impeller solidity ratio and ratio of hub to impeller diameter have influence on velocity distribution of impeller discharge flow.