Vietnam Airlines from Singapore to Beijing has 2 flights every day. And there are 6 flights per week flying out of Singapore which connect to Beijing.
The price for economy class – one way ticket of Vietnam Airlines from Singapore to Beijing is 12.515.000 VND (or ~$624 USD) and the price for bussiness class – one way ticket of Vietnam Airline is 21.758.000 VND (or ~$1086 USD).