In this paper, we report an investigation on Polarization Beam Combining (PBC) of two laser beams through simulation and experimental studies. The polarization beam combining of two 100 W fiber laser beams with overall efficiency 98% has been demonstrated. We have compared the output beam stability and efficiency in both coherent and incoherent cases for different power levels. Simulations shows that the combined beam intensity and its stability are not degraded significantly due to phase correlation between beams, which is validated through our experimental results. © 2020 SPIE.