The pseudo capacitive flexible pressure sensor based on reversible redox reaction has high sensitivity and can be used for weak pressure detection. However, currently, the linearity of the pseudo capacitive flexible pressure sensor is poor and can only maintain high sensitivity within a limited pressure range. For this reason, this paper uses MXene material as the electrode to design a double scale random microstructure ionic gel film with pores inside and rough surface, which increases the buffer space during the compression process, makes the stress deformation of the gel film more uniform, and ensures that the sensitivity remains stable during the compression process. Experimental data shows that the sensor has ultra-high linearity ( correlation coefficient ~ 0. 994) in the range of 0 ~ 1 MPa, excellent sensitivity ( ~ 2 133. 7 kPa -1 ), fast response and recovery time ( ~ 15 and~ 23 ms respectively), low detection limit ( ~ 2. 5 Pa), and excellent mechanical stability. The sensor can be used underwater to detect water depth with high linearity, and at the same time, the sensor can detect weak water flow changes caused by propeller disturbances at different water depths with high sensitivity.