To solve the defect which is recognizing but not rating the stress,or rating but not considering the influence of the previous stress state to the current state of the existing affective stress evaluation method,this paper proposes an approach of affective stress rating model on electrocardiogram(ECG).An affective stress rating algorithm based on hidden Markov model(HMM)was established with the theory of affective computing.The individual’s affective stress was rated using this affective rating model combining the investigation questionnaire.Features like complexity and approximate entropy of ECG were used in the model,and a matching process suggested that it improved the accuracy of affective stress rating.The result of the experiment illustrated that the model considering the environmental factors and the influence of previous stress state to the current state was an effective method in affective stress rating,and the accuracy of rating was improved by this affective stress rating method.