Days in Australia don't have any relevance now. The ATO use a residency test to determine if you are a resident for tax purposes. If you are then you can claim any tax paid in China as a credit then any additional that would have been paid if the same income was earnt in Australia must then be paid to the Australian tax dept.
The important thing for a Job in China ( if residing in Australia ) would be determining what tax is actually paid in China ( and can be claimed as a credit ) and what type of documention the company will provide as evidence of payment.
Australian taxation is all about self assessment. So you can do what you want, however if you get audited you need to be ready to prove you have complied with the law or face some eye watering fines and back taxes!!!