It is necessary to diagnose the combustion characteristic to improve the engine performance and fuel consumption. This is the reason why the many researches have been done to measure the temperature and pressure in combustion chamber. Of course, there are several methods, but they are proper only to laboratory scale not to commercial automotive due to their cost and difficulty of installation. So during the last few decades, the increasing interest and requirement for detection of combustion phenomena has led to the implementation of several different sensor technologies.This paper introduces a new method to predict the temperature of combustion chamber in vicinity of spark plug during the combustion period. A model which is utilized in this study is based on a breakdown voltage analysis, which relate the density of gas inside the combustion chamber. To verify the result of this method, it is compared with the 2-zone model of heat release rate.