Experimental results of a proto-type optical sampling oscilloscope based on sum frequency generation in periodically poled lithium niobate are demonstrated. The measurement performances under different conditions, like optical signal power, data rate, chromatic dispersion and wavelength, are estimated. Compared with the measured results by an Agilent 86100A oscilloscope, the optical sampling oscilloscope has higher sensitivity and is robust to weak signal. The measured results of optical signals with different data rates show that the proto-type optical sampling oscilloscope is adaptive and transparent to different data rates. Measured results under different chromatic dispersion values show that the optical sampling oscilloscope can measure optical signals from the fiber link. Measured results of optical signals with different wavelengths indicate that, in order to make the optical sampling oscilloscope have the identical performance for measuring the wavelength division multiplexing (WDM) signal, the spectrum of mode-locked laser should be as flattened as possible. The measured results by the proto-type optical sampling oscilloscope make sense for the future design and specification.