Researches on constructing English sentiment lexicon is relatively mature, and there are abundant and reliable lexical resources. Whereas for Chinese studies, the research history is short, and there are only a few Chinese sentiment lexicon resources. With reliable English sentiment lexicon as reference, an automatic constructing approach was proposed, based on semantic relationships. Firstly the Chinese sememe and words were extracted from the defination of concepts in HowNet and the semantic analysis was carried out upon them; secondly the sentimental value of each sememe and word was retrieved from the English sentiment lexicon SentiWordNet according to the DEF attributes of concepts in HowNet, and the final sentimental value of each word was calculated on the semantic relations of the sememe and words. The ready English lexicon was used without manual labeling in the method, and diverse information of words was recorded in the final lexicon, including semantic relations and sentimental values, which remedy the lack of other lexicons. The experimental results show that the resulted sentiment lexicon can achieve better performance in the recall and F value measurements under the condition of approaching other lexicons on the precision measurements.