The thin-walled grapefruit microstructured fiber and single-mode fiber are welded by fiber fusion technology to make a probe-type pressure sensor. The open air hole at one end of the microstructure fiber can communicate with the external pressure to realize the pressure response. The pressure sensitivity of 0.70 nm/MPa is obtained and the pressure response has good linearity. Through the comparison between the finite element simulation and experimental result, it is found that the microstructured fiber sensor has the interference of LP₀₁ and LP₁₁ modes, and it is proved that the sensor has good stability and repeatability.