In order to solve the problem of low temperature and pressure sensitivity of the existing fiber Bragg grating (FBG) sensors, a thin-walled cylindrical liquid temperature and pressure sensor based on FBG was designed. Both the stainless steel 304 and beryllium bronze C17200 with corrosion resistance, good elasticity, and high coefficient of thermal expansion were used to package the sensor. The finite element analysis method was used to simulate the pressure and temperature characteristics of the sensor. The influence of the material and size of the sensitive element on the sensitivity was studied, and the relationship between the reflection wavelength and the pressure and temperature was analyzed. The results show that the sensor encapsulated with beryllium bronze C17200 has higher pressure and temperature sensitivity, which can respectively reach 153.5pm/MPa and 31.7pm/℃ in the operating range of 0MPa~12MPa and -5℃~40℃, which are increased by 51.2 times and 2.8 times respectively on the basis of the bare grating, respectively. It is expected to be applied to high sensitivity measurement of liquid temperature and pressure. The results can provide reference for high sensitivity temperature and pressure measurement of liquid.