The tunable mid-infrared femtosecond sources with broadband， tunable wavelength， stable carrier envelope phase and high average power are achievable through optical parametric amplification. In this review， the key techniques of optical parametric ampification systems working in the mid-infrared range are introduced， including but not limited， broadband optical parametrical amplification and dispersion manging techniques. After that， the research progress and development prospect of the mid-infrared femtosecond source based on optical parametric amplification are presented and discussed.