The collaboration of scientific research is becoming more intensive, especially in interdisciplinary subjects. Complex network theory can be explored to demonstrate the characteristics of the scientific collaboration. This paper analyzes the co-author networks from 3 important journals in Chinese system engineering field in recent years using complex network theory. Scientific papers published on selected journals are used to construct the scientific collaboration networks. Statistical properties measuring the clusters of the constructed networks and influence of authors are studied. Empirical results show that the networks have two important features: small world effect and scale-free property, derived from the small average shortest path length, large average clustering coefficients and the power law of degree distributions of these networks. Besides, the structure of graphs in scientific collaboration networks is revealed and analyzed. Based on this analysis, the research groups that are active in the field of system engineering in China can be discovered in a qualitative way.