In a Class of Her Own 1990

Xue Wenxi comes from an impoverished family, and disguises as a guy to make ends meet by helping to transcript and copywrite books. She meets Feng Chengjun, the son of the Prime Minister, during a business transaction. Coming to admire her talent, Feng Chengjun secretly sets a plan in motion that leaves her with no choice but to enroll in the the Yun Shang Academy. As the school only accepts male students, Xue Wenxi disguises herself as a boy (renaming herself as Xue Wenbin), and lives everyday on thin ice to guard her secret. Fortunately, she has Feng Chengjun to come to her aid, allowing her to focus on her studies.