My mother works in China; I am nineteen (19) years old want want go to China and live there with her

You should go to the embassy or consulate general to apply for an S2 type. Prepare the following documents beforehand: a valid passport and a photocopy of its data page, a fully filled application form, a recently taken photo, a pohotocopy of your mother's passport and resident permit in China, an invitation letter from your mom, and a photocopy of your birth certificate.