To solve the sensitivity and nonlinearity of pressure sensor of microelectromechanical system (MEMS), Proposed a beam-composite membrane-island pressure-sensing structure, Optimize the overall structure size to obtain the maximum horizontal stress difference and deflection, Doping type, doping concentration, structure size and distribution position, And comparing the beam-composite membrane-island structure with the output of conventional structures, According to the simulation results, the sensitivity of beam-composite membrane-island structure in the range of 0-60 kPa pressure is increased by more than 7% higher than the related structure and 2 times higher than the E-type structure, The nonlinearity of 0.029% FSS, Meet the requirements of high sensitivity and high linearity of MEMS micro pressure pressure sensor, It can support the relevant applied research in the medical field.