  Based on the study of the string model methods of singly heavy mesons and
singly heavy baryons, we calculate the mass spectrum of $1S$-and $2S$-wave for
both charm and bottom mesons$(D/D_{s}, B/B_{s})$. Experimentally, there are
most masses spectra of $1S$-wave have been found, while the masses part of the
$2S$-state is not determined. In this paper, we will use singly light quark or
diquark model images and Regge trajectory models, combined with perturbation
processing methods, to analyze and study the observed singly heavy mesons,
further predict the unobserved mesons masses and their corresponding
spin-parity quantum numbers.
