To meet needs of design analysis and engineering application,this paper presents a mechanical model for a sensor using metal core piezoelectric fibers(MPFs).The expressions of the electric charges generating on the electrodes of MPF under an axial force or strain were derived from the constitutive equations.The electric charges of the MPF with platinum and wolfram cores,and different radius ratios of the metal core to the fiber were calculated repectively when they were subjected to a constant axial force or strain.The effects of the radius ratio on the electric charge of the MPF sensor were investigated.The quasi-static and dynamic strain sensing properties of different MPF sensors were experimentally studied.The first and the second order of natural frequencies of a uniform strength beam were tested by using MPF sensor.Experimental results indicate that the maximum sensitivity of the MPF sensor is 0.163C/με,and the sensor can give a high sensitivity for the quasi-static,dynamic strain and impact loads.