What bad things can immigrants do in Australia?

You mean a three-month multiple-entry tourist visa at a time. Will you stay in Australia for three months after your first visit and never come home again? In this case, it is against the terms of the visa. You can't stay there forever. As long as you leave this country, your passport will be stamped to indicate your departure date. In this way, if you want to enter the country next time, the customs may not allow you to enter the country, and your future application for various visas in Australia will be seriously affected, because you have violated the visa terms once, and the visa officer has every reason to refuse your future application. So don't stay too long, even for a day! Similarly, if you return to China on time every time, your previous good record will be very helpful for your next visa application. The materials you need to prepare are not so strict, and your visa will be approved soon.