Ever since the advent of transistor, the growth of integrated circuit(IC) has been remarkable one. Now ICs have penetrated and been absorbed into our daily lives. They are literally everywhere ?? not only in electronic devices such as computer and calculator, but also in mechanical devices like car, airplane, elevator and so on. Although this made the system safer and more convenient, mechanical system produces noise and degrade performance of electronic devices. In this paper, the effect of noise on VGA of UHF RFID reader system in automotive vehicle is analyzed. The critical noise path is defined and the effect of noise is modeled. Then the noise environment of automotive vehicle is defined. The characteristic of the noise environment is examined and the result is analyzed with modeled VGA.