In order to realize simultaneous measurement of magnetic field and temperature,a composite sensing structure based on the magnetic-volume effect of magnetic fluid (MF),a Fabry-Perot (FP) cavity and fiber Bragg grating (FBG) cascaded structure is proposed and fabricated.The FP cavity formed by the liquid interface of the MF injected into the hollow-core fiber (HF) and the end face of the single-mode fiber are both sensitive to magnetic field and temperature,and the cascaded FBG is only sensitive to temperature.By simultaneously monitoring the wavelength drift of FP cavity characteristic peak and FBG Bragg reflection peak,the magnetic field and temperature sensitivity coefficient matrix is used to obtain the temperature and magnetic field information simultaneously.An FBG-FP temperature and magnetic field dual parameter sensor with an initial cavity length of 56.1 μm is successfully fabricated,of which the magnetic field and temperature sensitivity of are 16.21 pm/Oe and 9.96 pm/℃,respectively.The sensor has the characteristics of small volume,simple structure and low cost,which can be applied to solve the magnetic field strength and temperature cross-sensitivity problem of conventiaonl fiber-optic magnetic field sensors.