Abstract: The study on combine harvester driver fatigue is important and necessary to reduce the accidents, improve the operation efficiency and protect the health of the driver.In order to explore the change rule of combine harvester driver fatigue, monitoring experiment of combine harvester driver fatigue was carried out with John Deere S660 at Gegiushan farm of Bei'an Agricultural Reclamation Administration in Heilongjiang province from October 1, 2014 to October 7, 2014.The experiment was performed in sunny day during the forenoon to eliminate the influences of time and weather on the experiment.The crops harvested were soybean, and the conditions of test land were similar.The noise of cab was 95 dB (A), of which temperature basically remain unchanged.The monitoring equipment was RM-6240C multi-channel physiological signal acquisition processing system produced by Chengdu Instrument Factory with four channels and one interface of 12 lead ECG, which is suitable for multi-channel synchronous detection, records and analysis of human body physiological signal such as Electrocardiogram (ECG), blood pressure, muscle tension.Before the test, skin preparation work was carried out such as removing dead skin, oil and grease.ECG signals were measured by three electrodes method; The electrodes were pasted on three places, for instance between the fourth rib on the left armpit front, below the right clavicle middle and the lower right of xiphoid process, which were connected with the positive(red), the negative(green) and the reference (black) wire respectively.The sampling frequency of multi-channel physiological signal acquisition system was 1 kHz, scanning speed 0.2 cm/s, sensitivity 1 mV.The ECG data of 10 male drivers sitting quietly in the cab were recorded for 5 minutes before harvesting (marked as quiet segment), at the same time subjective fatigue questionnaire were finished.Then the ECG data of drivers were recorded for 120 minutes when combine harvester running at the speed of 8~10 km/h.Subjective fatigue questionnaire were filled in every 20minutes.The ECG data collected in driving were divided into 12 parts with 10 minutes per part.The ECG data both of quiet segment and 12 parts were denoised and detected for R waveform by the way of Wavelet Transform, and then the R-R interval value of each part was computed.Nonlinear dynamic index SampEn was selected as the characteristic parameter of fatigue testing which characterizes the complexity of heart rate variability.Firstly, the change curve of SampEn along with driving time and the scores of subjective fatigue degree at specified moment were achieved, and correlation analysis was researched between SampEn and scores of subjective fatigue degree.Secondly, driver fatigue occurred time was determined by the results of paired-samples T test of SampEn between quiet segment and other 12 parts.Finally, degrees of fatigue in straight section and that of turn section were compared by the results of paired-samples T test of SampEn between each section and quiet segment respectively.The results showed that the average values of SampEn significantly declined with the increase of the driving time.Pearson correlation coefficient between SampEn and subjective fatigue score was -0.824, which showed that their relationship was negatively significant.According to the results of paired-samples T test of SampEn between quiet segment and other 12 parts, the values of SampEn of the fifth part was significantly different from that of quiet segment(P＜0.05), and the values of SampEn of tenth part was very significantly different from that of quiet segment(P＜0.01), which indicated that combine harvester driver fatigue began to appear after 50 minutes, and deeped after 100 minutes.The values of SampEn in turn section was significantly different from that of quiet segment(P＜0.05), there was not significant difference between straight section and quiet segment(P＞0.05), and the values of SampEn in turn section was smaller than that of straight section, which indicated that degree of fatigue of the former was higher than that of the latter.Compared with the subjective evaluation method of driver fatigue, determining diver fatigue method according to the change of the value of SampEn can more accurately reflect the beginning and deepening period of combine harvester driver fatigue, and objectively reflect the driver's physical and mental fatigue status.