  The stellar kinematics of low-mass galaxies are usually observed to be very
unsmooth with significant kinematical fluctuations in small scales, which
cannot be consistent with the projected centrosymmetric stellar kinematics
obtained from commonly used dynamical models. In this work, we aim to test
whether the high degree of kinematical fluctuations affects the dynamical mass
estimate of galaxies. We use the asymmetry parameter $\eta$ obtained from the
$180^{\circ}$ rotation self-subtraction of stellar kinematics of galaxies to
quantify the degree of kinematical small-scale fluctuations. We use TNG50
numerical simulation to construct a large sample of mock galaxies with known
total masses, and then obtained the virial dynamical mass estimator of these
mock galaxies. We find that the dynamical masses within three-dimensional
$R_{\rm e}$ to the mock galaxy centres are overall averagely accurate within
around 0.1 dex under the symmetric assumption, while $R_{\rm e}$ means the
projected circularized half-stellar mass radius in this work. We study the
local virial mass estimation bias for mock galaxies of different $\eta$. The
maximum bias difference of two $\eta$ bins is around 0.16 dex, which with other
local biases may help apply the observational virial mass estimators obtained
from massive galaxies to other types of galaxies. We find that the Spearman's
$\rho$ of $\eta$ with the intrinsic mass estimation deviations is near zero if
the local bias is eliminated properly. The results indicate that even for
low-mass galaxies, the existence of high degree of kinematical small-scale
fluctuations does not affect the measurement of the dynamical mass of galaxies.
