The time and frequency domain analysis for multicomponent non–stationary signals like Electrocardiogram (ECG) is an important issue in signal processing. Because of its non stationary, multicomponent nature, the use of time and frequency domain analysis can be very useful to identify the exact multicomponent structure of these biological signals. In this paper we have analyzed the ECG signal in time domain and calculated various statistical parameters and the study of different plots were done. Then we headed on the frequency analysis where the power spectral density is calculated using Welch method.