  As an eclipsing polar with 3.39 hrs orbital period, MN Hya was going through
state change when we observed it during 2009-2016. 10 new mid-eclipse times,
along with others obtained from literature, allow us to give a new ephemeris.
The residuals of linear fit show that period decreased during the phase of
state change. It means angular momentum was lost during this phase. The X-ray
observation indicates the mass accretion rate as about
$3.6\times10^{-9}M_{\odot}yr^{-1}$. The period decrease gives that at least 60
percent of mass being transfered from secondary was lost, maybe in form of the
spherically symmetric stellar wind. In high state, the data shows the intensity
of the flickering reduced when system had higher accretion rate, and that
flickering sticks out with primary timescale about 2 minutes, which implies the
position of the threading point as about 30 radius of the white dwarf above the
surface of it. The trend of light curves of the system in high state follows
that of low state for a large fraction of phase interval from phase 0 to phase
0.4 since which the cyclotron feature is visible, and the primary intensity
hump of light curves near phase 0.7 when the system is in high state did not
appear on the curve when it is in low state. Those facts contradict the
predictions of the two-pole model.
