It is very hard for your wife to change her tourist visa into work visa within Mainland China. She can apply for Work Visa as your dependent in Australia. You should send the copy of your passport, work permit and China residence permit to your wife, the marriage license is also required. Your wife can apply for residence permit within 30 days after entry if she hold the work visa as dependent. Then she can stay in China for about 6 months.

If she wants to apply for tourist visa, she can asks for 6 months stay duration for family visit, the final decision is up to the visa officer, the above documents are also required to show your relationship and your status in China.