Feature point obtaining and waveform drawing

The invention relates to the technical field of waveform drawing, and provides a feature point obtaining method and device and a waveform drawing method and device. The feature point obtaining method includes the steps of S1, calculating the logical distance SP between adjacent points on waveform data; S2, obtaining a set of waveform points on one logical point; S3, obtaining initial points, terminal points and extreme points in the set to serve as feature points. As the number of the obtained feature points is multiple and the feature points include the initial points, the terminal points and the extreme points, waveform distortion caused when waveform key points are lost can be avoided.