In recent decades, ultra-intense ultrashort pulse is an important trend in the development of laser optics. Especially in the mid-infrared (MIR) band, because the mid-infrared wavelength has greater ponderomotive force and its spectral range contains almost all the molecular "fingerprint" resonance peaks, the research of mid-infrared laser is very important in the fields of strong-field physics, mid-infrared spectroscopy, material processing and biomedical research. At present, there are many mature techniques for pulse shaping and amplification, such as different frequency generation (DFG), chirped pulse amplification (CPA), optical parametric amplification (OPA) and optical parametric chirped pulse amplification (OPCPA). Using optical parametric chirped pulse amplification technology with its advantages of high amplification gain, high signal-to-noise ratio and wide gain bandwidth to amplify the pulse in nonlinear crystals with high nonlinear coefficient has become one of the main means to obtain ultra-short and ultra-intense mid-infrared pulse.This paper summarizes the research progress of generating and amplifying MIR few-cycle pulse in 2-20 μm based on OPCPA , and its applications in strong-field physics, molecular spectrum detection and biomedicine are briefly described.