This paper presents the performance characteristics evaluation of MEMS capacitive pressure sensor. This type of absolute pressure measuring sensor is used for pulse rate measurement. Polysilicon material provides a higher sensitivity when chosen as diaphragm material. Two MEMS capacitive pressure sensors with varying geometries are analyzed in Matlab simulation software. The geometries are very common having parallel plates with spring loaded. In first stage the shape of the parallel plates is circular and in second case of the parallel plate is square. During modeling of these two diffident shaped sensors, the area of parallel plates in both cases is considered as equal. Once the geometries are formed, the electromechanical analyses have been performed. It is observed that these types of pressure sensors can withstand a wide range of absolute pressure from kilo Pascals to several order of mega Pascals. In this work, Matlab environment is employed to model this sensor and accurate model is devised to study its performance. Simulation results are obtained and compared with published work of FEM (Finite Element Method) based Multiphysics simulation platform and full argument is obtained. The proposed model allows handling different parameters affecting the performance of this sensor.