Huan zhu ge ge (1998)

A street girl, Xiao Yan Zi, in a mix-up ends up as a Princess (officially titled Huan Zhu Ge Ge) instead of her sworn sister (played by Ruby Lin). The adventures continue as Xiao Yan Zi tries to adjust to palace life, falls in love with the fifth prince (played by Alec Su), makes enemies with the Empress, and all the while trying to give her sworn sister back the title of Princess.