  The detection of GW190521 gains huge attention because it is the most massive
binary that LIGO and Virgo ever confidently detected until the release of
GWTC-3 (GW190426_190642 is more massive), and it is the first black hole merger
whose remnant is believed to be an intermediate mass black hole. Furthermore,
the primary black hole mass falls in the black hole mass gap, where the
pair-instability supernova prevents the formation of astrophysical black holes
in this range. In this paper, we systematically explore the prospect of TianQin
on detecting GW190521-like sources. For sources with small orbital
eccentricities, (i) TianQin could resolve up to a dozen of sources with
signal-to-noise ratio (SNR) larger than 8. Even if the signal-to-noise ratio
threshold increases to 12, TianQin could still detect GW190521-like binaries.
(ii) The parameters of sources merging within several years would be precisely
recovered. The precision of coalescence time and sky localization closes to $1\
{\rm s}$ and $1\ {\rm deg^{2}}$ respectively. This indicates that TianQin could
provide early warnings for ground-based gravitational waves detectors and
electromagnetic telescopes for these sources. Furthermore, TianQin could
distinguish the formation channels of these sources by measuring the orbital
eccentricities with a relative precision of $10^{-4}$. (iii) TianQin could
constrain the Hubble constant with a $10\%$ precision with GW190521-like
sources. Finally, for very eccentric GW190521-like sources, although their
gravitational wave signal might be too weak for TianQin to detect, even the
null detection of TianQin could still present a significant contribution to the
understanding of the underlying science.
