We realized closed loop control system of BBO optical parametric oscillation tuning system, by using American General Scanning Inc.'s controller to control BBO crystal's rotation, and demarcated the output wavelength with charge coupled device (CCD). The system's relative wavelength tuning error was less than 0.04%. We also demonstrated 0.347 μm pumped type Ⅰ phase matching BBO optical parametric oscillation's theoretical and experimental curve of output wavelength versus pumped light incidence angle.