The invention belongs to the technical field of medicine, and provides an R-wave extraction method for ECG signals, a system method and a system. The method comprises the steps of collecting an original ECG signal; subjecting the collected ECG signal to filtering treatment so as to obtain a processed signal; and extracting R waves out of a sequence corresponding to the processed signal based on the self-adaptive threshold algorithm. According to the invention, R waves are extracted based on the self-adaptive threshold algorithm. Namely, a reference threshold for the extraction of subsequent R waves is adjusted based on the parameters of previous R waves. As a result, the extraction accuracy of R waves is improved to a certain degree. The filtering treatment is conducted before the R-wave extraction step, so that noises in original ECG signals and the baseline drift phenomenon are effectively eliminated. The extraction accuracy of R waves is further improved.