  We perform high-resolution hydrodynamical simulations using the framework of
{\it MACER} to investigate supermassive black hole (SMBH) feeding and feedback
in a massive compact galaxy, which has a small effective radius but a large
stellar mass, with a simulation duration of 10 Gyr. We compare the results with
a reference galaxy with a similar stellar mass but a less concentrated stellar
density distribution, as typically found in local elliptical galaxies. We find
that about 10% of the time, the compact galaxy develops multi-phase gas within
a few kpc, but the accretion flow through the inner boundary below the Bondi
radius is always a single phase. The inflow rate in the compact galaxy is
several times larger than in the reference galaxy, mainly due to the higher gas
density caused by the more compact stellar distribution. Such a higher inflow
rate results in stronger SMBH feeding and feedback and a larger fountain-like
inflow-outflow structure. Compared to the reference galaxy, the star formation
rate in the compact galaxy is roughly two orders of magnitude higher but is
still low enough to be considered quiescent. Over the whole evolution period,
the black hole mass grows by $\sim$50% in the compact galaxy, much larger than
the value of $\sim$ 3% in the reference galaxy.
