  Dwarf spheroidal galaxies have a large mass to light ratio and low
astrophysical background, and are therefore considered one of the most
promising targets for dark matter searches in the gamma-ray band. By applying a
joint likelihood analysis, the power of resultant limits in case of no
detection can be enhanced and robust constraints on the dark matter parameter
space can be obtained. We present results from a combined analysis of 10 dwarf
spheroidal galaxies using Fermi-LAT data. Different annihilation channels have
been analyzed and uncertainties from astrophysical properties have been taken
into account.
