Lattice-matched InGaP on GaAs (001) was successfully grown by solid-source molecular beam epitaxy with a GaP decomposition source. A 0.5-μm-thick InGaP epilayer shows photoluminescence peak energy as large as 1.991eV at 15K, the full width at half maximum as small as 9.4meV and x-ray diffraction rocking curve linewidth as narrow as 25 arcsec. The electron mobilities of undoped and Si-doped InGaP layers obtained by Hall measurements are comparable to similar InGaP/GaAs heterojunction grown by solid-source molecular beam epitaxy with other sources or other growth techniques. The results reveal that the InGaP/GaAs heterojunction grown by the present growth way have great potential applications for semiconductor devices.