Based on a photonic crystal fiber (PCF) with zero-dispersion wavelength of about 1020 nm, fiber optical parametric amplifier (OPA) is investigated in detail. In order to obtain sufficient parametric gain in a rather short length of fiber, a passively mode-locked ytterbium fiber laser is built up to act as the pump seed, and pulse with high peak power is utilized to pump. The amplified short pulse from the mode-locked fiber laser is launched into the PCF to pump. Once the pump central wavelength approaches the zero-dispersion wavelength, significant parametric gain can be observed. The evolutions of parametric gain spectra versus different pump powers and pump wavelengths are investigated. The maximum parametric gain reaches 23 dB from experiment.