The importance of electronic security is now an important term in the global world. Due to the lack of modern security equipments we often face problems and lose our valuable assets. Though there are some security system are available in the market but wireless system are not so common and economic to us. Therefore, a Microcontroller Based Security System has been developed to recover that limitation. It can be used for ensuring fire security in Offices, Banks, Apartments, Industry and so on. The system detects the fire fault situation and inform automatically to the desired destination without any human intervention. Microcontroller Based Security System is an intelligent stand alone system with proven performance and stability. The aim of an engineering design is to produce maximum output with minimum cost involved. According to that, our designed system involves low cost yet offers better performance in comparison to other security system available. Microcontroller is the heart in our security system which is interfaced with smoke sensors, SIMCom GSM Module, alarm circuit and LCD display unit.