  The X9.3 flare SOL20170906T11:55 was observed by the CsI detector aboard the
first Chinese X-ray observatory Hard X-ray Modulation telescope (Insight-HXMT).
By using wavelets method, we report about 22 s quasiperiodic pulsations(QPPs)
during the impulsive phase. And the spectra from 100 keV to 800 keV showed the
evolution with the gamma-ray flux, of a power-law photon index from $\sim 1.8$
before the peak, $\sim 2.0$ around the flare peak, to $\sim 1.8$ again. The
gyrosynchrotron microwave spectral analysis reveals a $36.6 \pm 0.6 \arcsec$
radius gyrosynchrotron source with mean transverse magnetic field around 608.2
Gauss, and the penetrated $\ge$ 10 keV non-thermal electron density is about
$10^{6.7} \mathrm{cm}^{-3}$ at peak time. The magnetic field strength followed
the evolution of high-frequency radio flux. Further gyrosynchrotron source
modeling analysis implies that there exists a quite steady gyrosynchrotron
source, the non-thermal electron density and transverse magnetic field
evolution are similar to higher-frequency light curves. The temporally spectral
analysis reveals that those non-thermal electrons are accelerated by repeated
magnetic reconnection, likely from a lower corona source.
