The high-quality highly (100) oriented diamond films each with controllable surface morphology, quality, orientation, and growth rate are prepared at low pressure by microwave plasma chemical vapor deposition. The results show that there is a coupled effect between substrate temperature and methane concentration on the growth of (100) oriented diamond films. The substrate temperature should be increased with increasing the methane concentration in order to obtain similar surface morphologies. When the methane concentration is 3.0%, the results indicate that there are five states for the orientation change with the substrate temperature increasing from 740 ℃ to 1100 ℃, and the diamond films with (100) orientation can be deposited at the substrate temperatures ranging from 860 ℃ to 930 ℃. Moreover, the quality and growth rate of each of (100) oriented diamond films are proportional to the substrate temperature and methane concentration, respectively. In order to obtain the high-quality highly (100) oriented diamond films, the substrate temperature and methane concentration should be both appropriate.