  In this work, the support vector machine (SVM) method is adopted to separate
BL Lacertae objects (BL Lacs) and flat spectrum radio quasars (FSRQs) in the
plots of photon spectrum index against the photon flux, $\alpha_{\rm ph} \sim
{\rm log}\,F$, that of photon spectrum index against the variability index,
$\alpha_{\rm ph} \sim {\rm log}\, \textit{V\!I}$, and that of variability index
against the photon flux, ${\rm log}\,{V\!I} \sim {\rm log}\,F$. Then we used
the dividing lines to tell BL Lacs from FSRQs in the blazars candidates of
uncertain types from \textit{Fermi}/LAT catalogue. Our main conclusions are: 1.
We separate BL Lacs and FSRQs by $\alpha_{\rm ph} = -0.123\,{\rm log}\,F +
1.170$ in the $\alpha_{\rm ph} \sim {\rm log}\,F$ plot, $\alpha_{\rm ph} =
-0.161\,{\rm log}\,{V\!I} + 2.594$ in the $\alpha_{\rm ph} \sim {\rm
log}\,{V\!I}$ plot, and ${\rm log}\,{V\!I} = 0.792\,{\rm log}\,F + 9.203$ in
the ${\rm log}\,{V\!I} \sim {\rm log}\,F$ plot. 2. We obtained 932 BL Lac
candidates and possible BL Lac candidates, and 585 FSRQ candidates and possible
FSRQ candidates. 3. Some discussions are given for comparisons with those in
literature.
