  The Neupert effect refers to the strong correlation between the soft X-ray
(SXR) light curve and the time-integrated hard X-rays (HXR) or microwave flux,
which is frequently observed in solar flares. In this article, we therefore
utilized the newly launched Hard X-ray Imager (HXI) on board the Advanced
Space-based Solar Observatory to investigate the Neupert effect during solar
flares. By checking the HXR light curves at 20-50 keV, a sample of 149 events
that cover the flare impulsive phase were selected. Then, we performed a
cross-correlation analysis between the HXR fluence (i.e., the time integral of
the HXR flux) and the SXR 1-8 A flux measured by the Geostationary Operational
Environmental Satellite. All the selected flares show high correlation
coefficients (>0.90), which seem to be independent of the flare location and
class. The HXR fluences tend to increase linearly with the SXR peak fluxes. Our
observations indicate that all the selected flares obey the Neupert effect.
