Can I use Mi Zige in the calligraphy grade exam?

You can't.

Mi Zige or checkered calligraphy is usually used for calligraphy grading test. Generally speaking, the grid homework depends on your grades. If you can get higher in the exam, write more words, so that the work paper will be bigger, and the lower work paper will write fewer words.

Some exams above CET-6 are more difficult, because there are many words to write and two fonts to write, so it is a bit slow.