the Virialization assumption, combining with widely accepted empirical relation to estimate size of BLR of AGN ($R_{BLR}\propto L^{\sim0.5}$, Bentz et al. 2006, 2009, Denney et al. 2010, Kaspi et al. 1996, 2000, 2005, Greene et al. 2010, Wang & Zhang 2003), we will have $$\begin{split}
M_{BH}&\propto R_{BLR}\times V(BLR)^2\\
&\propto L(H\alpha_B)^{\sim0.5}\times V^2(H\alpha_B)
\end{split}$$ where index $H\alpha_B$ means corresponding line parameters of broad H$\alpha$. Moreover, we can find that for individual object ($M_{BH}=constant$ and $L(H\alpha_B)\propto flux(H\alpha_B)$), $$\begin{split}
&L(H\alpha_B) \times V(H\alpha_B)^4 = constant \\
&flux(H\alpha_B) \times V(H\alpha_B)^4 = constant \\
&L(H\alpha_B) (or\ R_{BLR}\ or\ flux(H\alpha_B))\Uparrow\ \Longrightarrow\ V(H\alpha_B)\Downarrow
\end{split}$$ In other words, line width of broad emission lines is decreasing with line luminosity (size of BLR, continuum luminosity) increasing. The strong expected negative correlation, $R_{BLR}$ versus $V$, have been found and reported for several well mapped objects, such as NGC5548 (Bentz et al. 2007, Denney et al. 2010, Peterson et al. 2002, 2004, Wanders & Peterson 1996), NGC3783 and NGC7469 (Peterson et al. 2004), Arp151 (Park et al. 2012). Certainly, the correlation between $R_{BLR}$ and $V$ for 3C390.3 is also shown in Peterson et al. (2004), however, there is no one reliable correlation confirmed for 3C390.3, due to the less number of data points 