A double Sangac interference ring optical fiber pressure sensor based on vernier effect is proposed. The sensor uses polarization maintaining photonic crystal fiber (PM-PCF) as a sensitive unit to realize Sagnac interference and vernier effect for pressure sensitivity through different PCF lengths. The sensor uses PM-PCF embedded in the single-mode optical fiber to form the reference unit and pressure sensitive unit of the sensor, and the pressure sensing part of the Sagnac ring is packaged. The pressure characteristics of the parallel Sagnac ring pressure sensor are studied through experiments. The experimental results show that the maximum sensitivity of the pressure sensor is -54.491nm/MPa and the resolution is 0.367kPa in the pressure range of 0~2.4MPa. Compared with the Sagnac ring pressure sensor without vernier effect, its pressure sensitivity is amplified by 16.7 times. In addition, the sensor has the advantages of simple manufacture, solid structure and stable operation, which provides an alternative design scheme for the high-sensitivity pressure sensor.