In order to make the fish stock assessment for rational fishery management on some species of ocean large pelagic fish in offshore waters of Vietnam Centre, the Length-based Cohort Analysis and Thompson & Bell prediction models have been used. The obtained results showed that when yields of Yellow fin tuna (Thunnus albacares), Big eye tuna (Thunnus obesus) and Skipjack tuna (Katsuwonus pelamis) in 2009 are 5,557 tonnes, 6,641 tonnes and 17,831 tonnes, respectively, their biomasses in early this year are 44,112 tonnes, 68,208 tonnes and 111,906 tonnes, respectively. If the fishing effort of 2009 equal X= 1.0, for Yellow fin tuna, Big eye tuna and Skipjack tuna, their values of MSY, 6,678 tonnes/year, 8,479 tonnes/year and 19.319 tonnes/year, will be gained corresponding to X=2.8, X=3.2 and X=2.0, respectively.