Vietnam Airlines from Vientiane to Phnom Penh has 1 flight every day. And there are 7 flights per week flying out of Vientiane which connect to Phnom Penh.
The price for economy class – one way ticket of Vietnam Airlines from Vientiane to Phnom Penh is 6.722.000 VND (or ~$334 USD) and the price for bussiness class – one way ticket of Vietnam Airline is 9.196.000 VND (or ~$458 USD).