  In the work we search for the $\gamma$-ray signal from M33, one of the
biggest galaxies in the Local Group, by using the Pass 8 data of Fermi Large
Area Telescope (LAT). No statistically significant gamma-ray emission has been
detected in the direction of M33 and we report a new upper limit of high energy
($>100\,\rm MeV$) photon flux of $2.3\times 10^{-9}\,\rm ph\,cm^{-2}\,s^{-1}$,
which is more strict than previous constrains and implies a cosmic ray density
of M33 lower than that speculated previously. Nevertheless the current limit is
still in agreement with the correlation of star formation rate and $\gamma$-ray
luminosity inferred from the Local group galaxies and a few nearby starburst
galaxies.
