Abstract: Objective using Heart Rate Variability（HRV） as mental level indexes, to find out the change of mental stress level and HRV indexes. Therefore, the study of ECG based on real-time acquisition of hardware systems and signal processing in the intelligent terminal, the HRV are extracted from ECG and the indexes are analyzed during writing task with mental pressure changes. The result shows that：When the stress increases, the Standard Deviation of the RR interval（SDNN）, the value of Total Energy（TP）, the value of Low Frequency（LF） and the value of LF/HF significantly increased, while the power value of High Frequency（HF） decreased obviously. Depending on the rate of rise and fall of various indicators, can divide the individual mental stress level. Thus, it is suggested that the five ECG indexes be used to reflect and evaluate the degree of mental pressure.

Key words: mental pressure, Heart Rate Variability（HRV）, time-frequency domain, intelligent terminal

摘要： 以心率变异性（HRV）作为应激水平的评价指标，分别探讨精神压力变化和HRV特征值变化的规律。基于对心电信号实时采集的硬件系统的研究，并在智能终端上进行信号处理，然后从中获取心率变异性（HRV）。通过做题任务，进而精神压力发生变化并对HRV特征值进行分析。实验结果发现，当人体产生压力时，HRV时域特征值中R-R间隔的标准偏差（SDNN）以及HRV频域特征值中总能量值（TP），低频功率密度值（LF）和LF/HF比值上升比较明显，然而高频段功率密度值HF却下降较明显，且根据各个指标的上升和下降的变化速率不同，划分个体的精神压力等级。因此，采用HRV时频域的五项特征值，可以对人体精神压力进行定量反映和评价。

关键词: 精神压力, 心率变异性, 时频域, 智能终端