Recently,a static magnetic perturbation field system consists of 5 saddle coils has been installed,and experiments of RMP impacting on locked mode and MHD suppression are taken.About 1.5 Gs threshold of extemal RMP to lock 2/1 mode at a certain discharging parameter is goffen,while the toroidal field is about 1.8T.It shows that the RMP is very helpful to suppress MHD oscillation at relatively low toroidal field and plasma current.However,it strongly depends on the spatial phase of external field,and the effects on MHD activity are thought to be the combined result of external RMP and intrinsic error field.In the meeting,we will give a detailed description of experiments and a simple analysis based on the calculation of magnetic field of the coils.