  In this contribution we present some results of potential energy surfaces of
actinide and transfermium nuclei from multi-dimensional constrained
relativistic mean field (MDC-RMF) models. Recently we developed
multi-dimensional constrained covariant density functional theories (MDC-CDFT)
in which all shape degrees of freedom $\beta_{\lambda\mu}$ with even $\mu$ are
allowed and the functional can be one of the following four forms: the meson
exchange or point-coupling nucleon interactions combined with the non-linear or
density-dependent couplings. In MDC-RMF models, the pairing correlations are
treated with the BCS method. With MDC-RMF models, the potential energy surfaces
of even-even actinide nuclei were investigated and the effect of triaxiality on
the fission barriers in these nuclei was discussed. The non-axial
reflection-asymmetric $\beta_{32}$ shape in some transfermium nuclei with
$N=150$, namely $^{246}$Cm, $^{248}$Cf, $^{250}$Fm, and $^{252}$No were also
studied.
