In order to improve the sensitivity of Mach-Zender（MZ） optical fiber strain sensor, a MZ optical fiber strain sensor sensitization demodulation system based on parallel cursor effect is designed. The system consists of a sensing interferometer and a reference interferometer in parallel, both of which are Mach-Zehnder interferometer（MZI） with a single mode fiber-no-core fiber-few-mode fiber-single mode fiber（SNFS） structure. By extracting the difference frequency components of two SNFS-MZI signals and tracking the movement of their troughs, the strain sensitivity of the system is improved. In addition, the temperature crosstalk during strain measurement is reduced by extracting the interference spectrum of the reference interferometer separately. The experimental results show that the strain sensitivity of the system is 7.39 pm/με, which is about 5 times that of a single sensor interferometer. By adjusting the sensing arm length of the reference interferometer and the sensing interferometer, the sensitivity performance of the MZ optical fiber strain sensor sensitization demodulation system can be flexibly adjusted.