  We conduct a detailed analysis of an M1.3 limb flare occurring on 2017 July
3, which have the X-ray observations recorded by multiple hard X-ray
telescopes, including Hard X-ray Modulation Telescope (Insight-HXMT), Ramaty
High Energy Solar Spectroscopic Imager (RHESSI), and The Fermi Gamma-ray Space
Telescope (FERMI). Joint analysis has also used the EUV imaging data from the
Atmospheric Imaging Assembly (AIA) aboard the Solar Dynamic Observatory. The
hard X-ray spectral and imaging evolution suggest a lower corona source, and
the non-thermal broken power law distribution has a rather low break energy
$\sim$ 15 keV. The EUV imaging shows a rather stable plasma configuration
before the hard X-ray peak phase, and accompanied by a filament eruption during
the hard X-ray flare peak phase. Hard X-ray image reconstruction from RHESSI
data only shows one foot point source. We also determined the DEM for the peak
phase by SDO/AIA data. The integrated EM beyond 10 MK at foot point onset after
the peak phase, while the $>$ 10 MK source around reconnection site began to
fade. The evolution of EM and hard X-ray source supports lower corona plasma
heating after non-thermal energy dissipation. The combination of hard X-ray
spectra and images during the limb flare provides the understanding on the
interchange of non-thermal and thermal energies, and relation between lower
corona heating and the upper corona instability.
