A new type optical fiber sensor which realized the simultaneous measurement of temperature, pressure and flow rate was proposed, and some research work on its principle, structure and process design was carried. The flow rate sensitization structure combined by target and cantilever, thin-walled cylinder pressure structure were integrated on a sensing probe, 4 fiber Bragg gratings (FBG) were adopted to measure the temperature, pressure and flow rate simultaneous. By making addition or difference between two pairs of FBG resonance wavelength shift, the cross sensitivity between temperature and flow rate, pressure was solved. Meanwhile, the calibration system was developed, this system can achieve relatively accurate calibration and measurement of the proposed multi-parameter sensor.