Abstract: Abstract: In the present study, a drag reduction on bionic surface originally inspired by the dolphin skin was designed and constructed. Two factors are coupled together with this bionic surface, they are bionic form processed on the basal rigid material and elastic surface material coupling on the bionic form. Such surface was called form/elastic material bionic coupling functional surface (BCFS) in this paper. The BCFS has been used in the impeller surface of centrifugal pump and proved to have the function of drag reduction. However, because of the limitation of existing test equipment, the drag reduction characteristics and mechanism of such BCFS can't be revealed effectively. As such it greatly affects the wide application of the BCFS. Thanks to the gradually maturing fluid-structure coupling simulation technology, it makes the fluid control research by the BCFS possible. The two-way fluid-structure coupling simulation method was used under the ANSYS-Workbench platform to study the characteristics of drag reduction affected by the two coupling factors: elastic modulus of elastic surface material and spacing of basal bionic form. We constructed three different BCFS models whose elastic modulus of surface materials were 2.8×104, 2.8×106 and 5×106 Pa, respectively under the condition of basal bionic form spacing of 2 mm. Those models were called model 1, model 2 and model 3, and their drag reduction characteristics were investigated. The simulated result showed that the smaller elastic modulus of surface material was the greater the elastic deformation of the surface material would be. So the phenomenon of elastic surface dynamic coupling with basal bionic form was more distinctively, and the fluid control ability of the BCFS became stronger, the total resistance would be reduced. We then constructed another three different BCFS models with bionic form spacing value d of 2, 3 and 4 mm, respectively under the condition of surface material elastic modulus was 5×106 Pa. They were called model 4, model 5 and model 6, and their drag reduction characteristics were studied. The simulation result showed that though the bionic form was under the elastic surface material, it had great influence on the drag reduction of BCFS, especially the spacing valued d of bionic form. The average wall shear stress and turbulent kinetic energy dissipation rate of the fluid-structure interface were larger with the increases of the bionic form spacing value d. The larger the spacing value d was, the stronger the wall shear stress would be, so the energy used to overcome the wall shear stress was also increased. This would lead to turbulent kinetic energy dissipation rate rising. Above simulation results indicated that choosing appropriate basal spacing value d would allow a better drag reduction effect. As for the drag reduction mechanism of BCFS, the deformation pushed the fluid-solid actual contact surface downward, the velocity gradient of the fluid boundary layer decreased, resulting in frictional force reduction. In addition, the elastic deformation absorbed some of the energy, effectively reducing the turbulent kinetic energy, avoiding excessive exchange and energy loss at the fluid-solid interface.