For the detection of physical parameters in miniature complex environments， especially involving refractive index and temperature detection to meet the requirements of high sensitivity， low cost， anti-electromagnetic interference， etc. In this paper， we proposed an ellipsoidal Fabry-Perot （F-P） cavity fiber optic probe sensor with simple preparation and novel structure. Firstly， a Single Mode Fiber （SMF） with a flat cut end face was inserted into a ceramic ferrule， and UV adhesive and Graphene Oxide （GO） were sequentially fixed on the end face of the SMF to form an ellipsoidal dual F-P cavity fiber probe sensor with an end cap structure. Then the refractive index （RI） and temperature characteristics of the sensor were theoretically analyzed and experimentally investigated. The experimental results show that the interferometric spectrum of this sensor is red-shifted with the increase of RI in the range of 1.353 2 to 1.391 2， and the RI sensitivity is 119.1 nm/RIU， and the linear correlation coefficient between RI and wavelength shift is 0.99； in the range of 20~60 ℃， the temperature sensitivity of the sensor is 116 pm/℃. The probe sensor designed in this paper has the advantages of simple structure， strong anti-interference ability， low production cost， stable output spectrum and small detection area. Meanwhile， the unique physicochemical properties of GO make it have good application prospects in the field of biological detection of various antigen molecules， bacteria and viruses.