Heteroepitaxy of InP on GaAs substrates by LP-MOCVD has been investigated experimentally. Low temperature (LT) GaAs and ultrathin LT InP buffer layers are grown at 450 ℃, which had composed the double metamorphic buffers together. In addition, In1-xGaxP/InP(x=7.4%) strained layer superlattices (SLSs) have been inserted into the normal InP epilayers. XRD curves of InP epilayers in (004) reflection have been compared under different thicknesses of LT GaAs buffer, different insertion positions and different periods of single InGaP/InP SLS. Insertion of double SLSs into InP epilayer has also been tried. In this experiment, the full width at half maximum (FWHM) values of XRD ω scan curves are only 370 arcsec and 219 arcsec for 1.2 μm and 2.5 μm-thick InP epilayers, respectively. Subsequently, 10-period In0.53Ga0.47As/InP MQW structure has been deposited on 2.5 μm-thick InP epilayer, the peak wavelength of room-temperature PL spectrum was located at 1625nm with the FWHM value of only 60 meV. Experimental results indicate that the heteroepitaxy scheme described in this paper would become a potential approach to realize the monolithic optoelectronic integration between InP and GaAs.