Sorry, I don't want a key-in. In batch-process (VBA RUN) if it is running too fast (I guess), it sometimes would be treated as a n unknown command and therefore unworkable. As John Frampton said rendering mode is different from display style. I eventually understood why the result is different from key-in.
Likely there're no solution. (I searched, no style relative to "display" in VBA). Ask for one more thing, is it possible to set Microstation V8i turning on "LEGACYDRAWORDER" automatically when opening a V7 dgn file? And then I don't need to upgrade them into V8 format and also the display style.