An in situ bending-plate method is used to measure intrinsic stress during the growth process of nanocrystalline-diamond film. Nanometer-sized diamond film is prepared by continuous H+ ion bombardment under different energies induced by applying a negative-bias voltage at the substrate relative to the grounded-vacuum chamber using the microwave-plasma, chemical-vapor-deposition (MWPCVD) method. The effects of substrate-bias voltage, temperature, total pressure, and CH4 concentration on intrinsic stress during the film-growth process are investigated. The results indicate that high bias voltage and high substrate temperature are beneficial when synthesizing smooth nanocrystalline-diamond film. This film usually relates to high intrinsic compressive stress. This stress can be attributed to the high secondary-nucleation rate and grain-boundary density. The evolution of intrinsic stress presents a complicated process at different pressures and CH4 concentrations. The compressive stress of the film can be controlled by modifying the grain size at various deposition parameters. (C) 2003 American Vacuum Society.