  We report the discovery of large amplitude X-ray variability in the low
luminosity AGN (LLAGN) MGC 7589, and present possible observational evidence
for accretion mode transition in this source. Long-term X-ray flux variations
by a factor of more than 50 are found using X-ray data obtained by Swift/XRT
and XMM-Newton over 17 years. Results of long-term monitoring data in the UV,
optical and infrared bands over ~20 years are also presented. The Eddington
ratio increased from $10^{-3}$ to $\sim0.13$, suggesting a transition of the
accretion flow from an ADAF to a standard thin accretion disc. Further evidence
supporting the thin disc in the high luminosity state is found by the detection
of a significant soft X-ray component in the X-ray spectrum. The temperature of
this component ($\sim19^{+15}_{-7}$eV, fitted with a blackbody model) is in
agreement with the predicted temperature of the inner region for a thin disc
around a black hole (BH) with mass of $\sim10^{7}\,M_{\mathrm{Sun}}$. These
results may indicate that NGC 7589 had experienced accretion mode transition
over a timescale of a few years, suggesting the idea that similar accretion
processes are at work for massive black hole and black hole X-ray binaries.
