  Motivated by the experimental progress in the study of heavy baryons, we
investigate the mass spectra of strange single heavy baryons in the
$\lambda$-mode, where the relativistic quark model and the infinitesimally
shifted Gaussian basis function method are employed. It is shown that the
experimental data can be well reproduced by the predicted masses. The root mean
square radii and radial probability density distributions of the wave functions
are analyzed in detail. Meanwhile, the mass spectra allow us to successfully
construct the Regge trajectories in the $(J,M^{2})$ plane. We also
preliminarily assign quantum numbers to the recently observed baryons,
including $\Xi_{c}(3055)$, $\Xi_{c}(3080)$, $\Xi_{c}(2930)$, $\Xi_{c}(2923)$,
$\Xi_{c}(2939)$, $\Xi_{c}(2965)$, $\Xi_{c}(2970)$, $\Xi_{c}(3123)$,
$\Xi_{b}(6100)$, $\Xi_{b}(6227)$, $\Xi_{b}(6327)$ and $\Xi_{b}(6333)$. At last,
the spectral structure of the strange single heavy baryons is shown.
Accordingly, we predict several new baryons that might be observed in
forthcoming experiments.
