  Motivated by recent high-energy electron and $\rm ^3H$ and $\rm ^3He$ nuclei
scattering experiment in Jefferson Lab (Nature 609, 41 (2022)), the short-range
correlations (SRCs) between nucleon pairs for 3-nucleon systems are
microscopically studied using realistic $NN$ 2-body interaction and
two-Gaussian type $NNN$ 3-body interaction. The wave functions of both $\rm
^3H$ and $\rm ^3He$ are obtained by solving 3-body Schr\"{o}dinger equations
using Gaussian expansion method (GEM). The differences of one-nucleon and
nucleon-nucleon momentum distributions between $\rm ^3H$ and $\rm ^3He$ are
analyzed in detail. The results show that the percentages of $pn$-SRC pairs are
significantly enhanced as compared with those of $nn(pp)$-SRC ones in $\rm ^3H$
and $\rm ^3He$ nuclei, which is consistent with the experimental findings.
