Abstract: According to the characteristics of DNB type CHF under high pressure, the constitutive correlations of Weisman & Pei model are proposed. The prediction results of three entrainment and deposition correlations of Kataoka, Celata and Hewitt corresponding to the Dry-out type CHF are analyzed. Based on the two improved models above, a comprehensive CHF mechanistic model under high pressure condition combined the DNB and Dry-out type boiling crisis is established. The verification based on the experiment database of upflow boiling in vertical round tube and the parametric trends analysis of CHF with thermal-hydraulic and geometric parameters are carried out.