The present disclosure relates to a method for analyzing an R-wave of an electrocardiogram (ECG) signal. The method includes obtaining an original ECG signal of a subject; filtering the original ECG signal; determining whether to trigger a search gate based on the filtered ECG signal, wherein the search gate is an instruction for detecting an R-wave on the original ECG signal; and detecting the R-wave on the original ECG signal in response to a determination of triggering the search gate.