Two-pump fiber optical parametric amplifier (FOPA) with two-section highly nonlinear fibers is proposed and demonstrated, which has broad bandwidth, high and flat gain. Using the fourth-order dispersion coefficient of the fibers as a pivotal factor, the optimization of the gain characteristics of the FOPA with double pumps and two section fibers is achieved. The FOPA with 424 nm bandwidth, 62.46 dB average gain and gain ripple less than 5 dB is obtained.