The important parameters that have significant effects on the prediction of CHF (Critical Heat Flux) were investigated. This was the preliminary study for a generalized CHF correlation in uniformly heated vertical round tubes. DKU-PDL CHF database[1] was used for this analysis. Four representative CHF data sets at pressure conditions of 1.01, 70, 140, and 200 bar were selected, analyzed, and compared to evaluate the effects other than the system pressure on the CHF. It has revealed that the major variables which influenced the CHF, other than the system pressure (P), were tube diameter (D), mass flux of water (G), and local true mass fraction of vapor (Xt). The parameters, square root of GXt and square root of D, were also determined to be significant in the parametric trends of the data sets. The results of this study have reaffirmed the feasibility that an advanced generalized CHF correlation for uniformly heated vertical round tubes can be found.