This paper theoretically studies the double-pumped fibre-optical parametric amplifiers (FOPAs) in photonic crystalfibres.Two distinct working regimes of FOPAs are researched,which depend on the dispersion at the central wavelengthof the two pumps.Extremely broad tuning range can he obtained when the central pump wavelength is in the normaldispersion regime and is insensitive to the wavelength separation between the two pumps,while the tuning range isnarrow in the anomalous dispersion regime and can be significantly enhanced by increasing the wavelength separation.Impacts of higher-order dispersions and temporal walk-off on the gain spectra are also discussed.