Thanks guys for the solution,
I've tried using synchronous tools also like SDETERS and Rob_N mentioned, with this method I did it, but I am not sure that the fillet still the same as before, it has forbidden to change the radius, any suggest ?
MrtZcn81 : I've tried your method, like select only one face and also all face, but still cannot do
MANox : can you give me a video, that similar with you suggests ?
Thank you guys, FYI, last week I tried to get new job as design engineer, and the test is like this one, and I failed, because I cannot add the thickness of the surface without change any radius/blend
I really want to know how to do that.