As the transmission bit rate increases to 10 Gb/s, especially 40 Gb/s and beyond, polarization effects in optical fibers have become one of the significant limiting factors for long-haul transmission. The polarization characteristics of fiber are mainly polarization mode dispersion (PMD) and polarization dependent loss (PDL). While the pulse root mean square (RMS) broadening is a main physical variable to judge signal transmission performance. The interaction between PMD and PDL and their combined effects on pulse broadening are investigated in detail. The relation between PMD vector and PDL vector in fiber links is described analytically. In presence of PMD and PDL, analytical expression of pulse broadening in optical fibers is derived, and chromatic dispersion, chirping are also considered simultaneously. The model can be used to analyze higher order PMD, PDL and pulse broadening in any linear fiber communication system.