This paper presents a fiber different pressure sensor based on intensity modulation,This sensor is composed of number of pressure sensing probes, the form of each probe is used to the fiber axis symmetric distribution, Using the analytical method to establish a mathematical model of light intensity modulation function M, this mathematical model showed a ratio of the received light intensity and entered light intensity, the ratio is mainly composed of the effective receiving area S and the reflected light cone end diameter R, finally using the simulation method to calculate the output light intensity ratio curve of the receiving fiber when the distance parameter was changed, and imposed a range of pressure P on the elasticity of thin slices, the results showed that the value of has little effect on the sensor measuring range. Finally, done the level monitoring experiment in one container, and obtained that the change of output signal and liquid level had the same trend.Studies have shown that, by this structure of the differential pressure sensor designed, can be achieved for different pressure range and accuracy detection.