Do I use a return ticket to travel to Russia for 30 days?

There is no need to use a return ticket.

You don't need a return ticket to travel to Russia. You only need a personal tourist visa to travel to Russia, and you don't need to buy a round-trip air ticket from China to Russia. But if you can't find it, you may need to buy a return ticket or a ticket to a third country. Generally speaking, you need to prepare a departure ticket, not necessarily a return trip, but if you leave the country, you won't check it.

If you need to return, you can buy a return ticket, and there may be some discounts. You can buy it when you are free. If the time is inconvenient, it is recommended not to buy it. You can also choose to buy a return ticket on the spot.