This paper proposes and prepares a new Mach-Zender interferometric sensor for structural health monitoring of solid rocket motors.The sensing structure is composed of a multimode fiber,an oxide-doped fiber and a multimode fiber (MMF),which are fused by hand in turn.Wherein the doped fiber is a sensing unit,the fiber core of the doped fiber is mainly formed by doping Y2O3,Al2O3 and P2O5,and the refractive index (RI) of the fiber core presents linear-like distribution.The theoretical model of the sensor is established,and the optical field transmission characteristics of the sensor are analyzed.The sensor samples are developed.Temperature,bending and strain experiments are carried out.The results show that the temperature,bending and strain sensitivities of the sensor are 57 pm/℃,9.41 nm/m-1 and 3 pm/με,respectively.Compared with the same type of sensor,the sensitivity is greatly improved,and the sensor shows different spectral characteristics.The sensor has the advantages of simple preparation process and compact structure,and can be applied to the measurement of multiple parameters such as temperature,bending and strain.