  Polarization measurements of the prompt emission in Gamma-ray Bursts (GRBs)
can provide diagnostic information for understanding the nature of the central
engine. POLAR is a compact polarimeter dedicated to the polarization
measurement of GRBs between 50-300 keV and is scheduled to be launched aboard
the Chinese Space Laboratory about year 2012. A preliminary Monte Carlo
simulation has been accomplished to attain the expected performance of POLAR,
while a prototype of POLAR is being constructed at the Institute of High Energy
Physics, Chinese Academy of Sciences. The modulation factor, efficiency and
effective area, background rates and Minimum Detectable Polarization (MDP) were
calculated for different detector configurations and trigger strategies. With
the optimized detector configuration and trigger strategy and the constraint of
total weight less than 30 kg, the primary science goal to determine whether
most GRBs are strongly polarized can be achieved, and about 9 GRBs/yr can be
detected with MDP < 10% for the conservative detector configuration
