The effect of total pressure on growth rate and quality of diamond films prepared by microwave plasma chemical vapor deposition was investigated. The results show that when the total pressure changed from 1.03×104 to 1.68×104Pa the growth rate increased from 3 to 16μm/h. For the diamond films prepared at high deposition pressure, scanning electron microscope images show clearly the crystals and the Raman spectra have sharp peaks at 1332 cm-1, which shows good quality of diamond films. However, the voltage-current relation shows the electrical quality of diamond films decreased since the defect density of surface may increase at high deposition pressures.