We propose a novel technique to achieve a high speed real-time optical sampling system based on optical parametric amplification in high nonlinear fiber (HNLF). Linearly chirped pulses are obtained by the dispersive propagation of short pulses emitted by a mode-locked fiber laser. The pulses are then fed into an HNLF together with signal under sampling. Thanks to the optical parametric amplification effect in the HNLF, the amplitude information will be modulated onto the linearly chirped pulses. By employing optical band-pass filters or wavelength division multiplexing (WDM) technology before the receivers, simultaneous high speed optical sampling and optical serial-to-parallel conversion are achieved. We demonstrate the feasibility of the scheme by optical sampling a 10 Gb/s on-off keying (OOK) signal at a sampling rate of 40GS/s and simultaneously converting it into four 10 GS/s sampling outputs. And the 10 Gb/s OOK signal is reconstructed later by the four sampling outputs. The scheme is simple and of low cost, which makes it a good candidate in high speed real-time sampling system.