Abstract: A new type of detected device based on electric field of human heart was investigated. The characteristic and method of calculation of rest potential was researched. Based on Wilson theory, a successfully model of electricity field of human heart was built and a new equation corresponding with rest potential was produced. After stimulation of equation, the result of distance of theory detected by human heart's electricity field and the best range of distance for human detected is 160 m and 20~60 m respectively. With analysis of corresponding relationship between rest potential and value of electricity field, the purpose of differentiating kinds of human and animal can be fulfilled.