  In this paper we visited mass spectra and decay constants of pseudoscalar and
vector heavy-light mesons ($B$, $B_s$, $D$ and $D_S$) in the framework of QCD
sum rule and quark model. The harmonic oscillator wave function was used in
quark model while a simple interpolating current was used in QCD sum rule
calculation. We obtained good results in accordance with the available
experimental data and theoretical studies.
