Due to the lack of solid gain medium,it is relatively difficult to produce mid-infrared laser directly by using the energy level of the gain medium. To solve this problem,the optical parametric amplification method based on nonlinear frequency conversion was designed to produce mid-infrared laser pulse. The accurately synchronous signal and pump light are produced by using developed high peak power near infrared laser. Optical parametric amplification was carried out by using the nonlinear effect of KTP crystal,and the laser pulse in mid-infrared wave band was obtained. The experiment results show that the center wavelength of the generated mid-infrared idler light is 3200 nm;the pulse energy is 14.9 μJ;the pulse width is 47 fs.