The invention discloses a photo plethysmograph multi-parameter analyzing method of a short autonomic nerve state and relates to a digital signal processing method. The method comprises the following steps of collecting a photo plethysmograph digital signal of the blood volume change of microvessel beds in the skin surface layer of a tested part; conducting the baseline removing treatment on the signal and detecting the peak value point and the valley value point of each beat of the plethysmograph; calculating and obtaining the parameters of interval, range and baseline; sectioning the photo plethysmograph and the three parameters within the time period smaller than one minute; respectively conducting the normalization treatment on the interval, the range and the baseline in the section and obtaining three Poincare plot quantitative indicators; respectively obtaining a first-order differential signal to the interval, the range and the baseline of the photo plethysmograph and calculating the relative coefficient of any two of the three parameters; analyzing the quantitative indicators and conducting the quantitative assessment of the autonomic nerve state through the value change. The photo plethysmograph multi-parameter analyzing method of the short autonomic nerve state can be possibly applied in clinical autonomic nerve state tracking analysis and daily household health monitoring.