An individual’s personal network is a basic object of study in sociology. This article analyzes and compares sina-weibo users’ personal network size based on over 2 billion tweets gathered from over 1.3 million users in 2012. We propose a new measure method for the analysis of user interactions based on how an individual divides his attention across contacts and how user’s characteristics affect the interactions. We find that the balance of attention of user with different age and gender is quite different in weibo. It displays interesting variation in both different groups of people and different modes of interaction. An individual’s personal network is a basic object of study in sociology. This article analyzes and compares sina-weibo users’ personal network size based on over 2 billion tweets gathered from over 1.3 million users in 2012. We propose a new measure method for the analysis of user interactions based on how an individual divides his attention across contacts and how user’s characteristics affect the interactions. We find that the balance of attention of user with different age and gender is quite different in weibo. It shows interesting variation in both different groups of people and different modes of interaction.