Abstract: Social networks based on binary relationships are very important for understanding people's sociality. People's social relationships largely determine the stability of social networks among which mobile communication is one of the typical way reflecting people's emotional connection. In this paper, we used a large mobile phone dataset from an area of China to study that how people build and maintain social relationships. To measure the uniformity of human emotional behavior, an entropy-based index is proposed and used to analyze the mobile phone data. The results reveals that there are obvious sex and age differences that people invest and assign their resources in social networks.