We report the effects of multi-layer InAs/InAlGaAs quantum dots (QDs) inserted as dislocation filters into an InP thin film epitaxially grown on (001) Si substrates by metalorganic chemical vapor deposition. The surface of the InP-on-Si template using 500 nm GaAs as an intermediate buffer is anti-phase-boundary-free. With the QD filters introduced, a four-fold reduction of dislocation density, to the order of 3.2x108/cm(2) was achieved, based on observation of large-area cross-sectional transmission electron microscopy (TEM). The dislocation filtering mechanism was further analyzed through zoomed-in TEM images. Bending or coalescence of threading dislocations in the presence of the strain field induced by the QD filters led to annihilation reactions. Moreover, the improved crystalline quality of the InP above the dislocation filters was manifested by enhanced intensities and reduced full-width at half-maximum values in the statistical room temperature photoluminescence spectra. These results indicate that introducing QD dislocation filters could be beneficial for the epitaxial growth of high quality 1.55 pm band lasers on a Si manufacturing platform.