An optimized fiber-optic Fabry-Perot sensor with a long cavity based on two chirped fiber Bragg gratings (CFBG) with same wavelength and bandwidth is proposed. The parameters of CFBG and Fabry-Perot sensor are optimized. According to the optimized parameters, an optimized Fabry-Perot sensor is formed. The strain experiment using optimized Fabry-Perot sensor has been carried out. The experimental results show that a strain accuracy of better than ±8 με is achieved.