Abstract: In order to improve the efficiency of hole digging and fertilization in orchards, the degree of human fatigue during hole digging and fertilization was studied. Portable gasoline fertilizer was taken as the object of this research. A subjective questionnaire was used to measure the degree of work fatigue and objectively test the physiological characteristics of the human body. Human heart rate（ECG）, respiratory rate（HESP）, and surface electromyography（EMG） were selected as the test indices to study the degree of fatigue in operators when using portable gasoline fertilizer after varying working times, and the fatigue degree of operator was evaluated. The experimental results showed that with increase in work frequency, the absolute value of person correlation coefficients of the objective physiological signals including human heart rate signal, respiratory rate signal, surface electromyography signal and the subjective questionnaire results were all greater than 0.8, and the correlation between subjective and objective measurement of fatigue test results was very strong. Using the weighted average method, the physical fatigue score and the mental fatigue score were combined, and it was observed that when the operation times were 12, the human body was in a “mild fatigue” state. When the operation times were 14, it reached the state of “moderate fatigue”, and when the operation times were 16, it entered the state of “moderate and severe fatigue”. The results provide the basis for the improvement and optimization of a portable gasoline fertilizer based on comfort, and also provide a reference for more objective evaluation of work fatigue.