Joal bearings are important parts to keep the high dynamic performance of rotor machinery.Some methods have already been proposed to analysis the flow field of joal bearings,and in most of these methods simplified physical model and classic Reynolds equation are always applied.While the application of the general computational fluid dynamics (CFD)-fluid structure interaction (FSI) techniques is more beneficial for analysis of the fluid field in a joal bearing when more detailed solutions are needed.This paper deals with the quasi-coupling calculation of transient fluid dynamics of oil film in joal bearings and rotor dynamics with CFD-FSI techniques.The fluid dynamics of oil film is calculated by applying the so-called dynamic mesh technique.A new mesh movement approach is presented while the dynamic mesh models provided by FLUENT are not suitable for the transient oil flow in joal bearings.The proposed mesh movement approach is based on the structured mesh.When the joal moves,the movement distance of every grid in the flow field of bearing can be calculated,and then the update of the volume mesh can be handled automatically by user defined function (UDF).The joal displacement at each time step is obtained by solving the moving equations of the rotor-bearing system under the known oil film force condition.A case study is carried out to calculate the locus of the joal center and pressure distribution of the joal in order to prove the feasibility of this method.The calculating results indicate that the proposed method can predict the transient flow field of a joal bearing in a rotor-bearing system where more realistic models are involved.The presented calculation method provides a basis for studying the nonlinear dynamic behavior of a general rotor-bearing system.