Abstract: By introducing the complex network theory and analyzing how cross -ownership impacts on the fluctuation of stock markets, this paper describes how two kinds of complex networks were established by cross -ownership relation of the listed companies of Shanghai and Shenzhen stock markets. The theoretical analysis and numeral value simulation show that, one network was a scale-free one based on choosing and self-regard connecting principle, and the other network was established by the price cross-correlation of listed companies with cross-ownership relation. A threshold was put forward and used to adjust the size of networks. This network can show scale-free property when the threshold equals to a specifically value. The research shows that the stock with large degrees can influence the whole network, and impact on the stock market further.