The breakthrough of high quality and high efficiency diamond doping is the premise of realizing high-performance diamond power electronic devices. In this paper, the homoepitaxial growth of high-quality boron doped single crystal diamond was prepared by MPCVD with trimethylboron as the source gas. The surface roughness is 0.35 nm, the full width at half maximum (FWHM) of XRD (004) rocking curves is 28.4 arcsec, and the FWHM of Raman spectrum is 3.05 cm-1. By changing the boron concentration in the gas component, the controlled p-type diamond doping with the concentration from 1016 cm-3 to 1020 cm-3 was realized. Then, the effects of deposition conditions such as B/C ratio, growth temperature and methane content on the electrical properties of p-type diamond were studied. The hole mobility of 207 cm2/(V·s) has been obtained with the B/C ratio of 20×10-6, the growth temperature of 1 100 ℃, the CH4/H2 ratio of 8% and the chamber pressure of 160 mbar. Furthermore, the crystal quality of boron doped diamond can be improved with the adding of oxygen in the gas component, that is to say, reducing the impurity scattering. When the O2/H2 ratio is 0.8%, the hole mobility increases significantly to 614 cm2/(V·s).