With the rapid development of network science, more and more researchers begin to study human language as a complex network. Based on Mongolian news corpus and TV interview corpus, this paper establishes written and spoken corpora, constructs four Mongolian word co-occurrence networks with morphological changes and non morphological changes, counts the common parameters of their complex networks, and discusses the complex network characteristics of Mongolian word co-occurrence networks. The experimental data show that the common parameters of the four Mongolian words co-occurrence network are significantly different; The four co-occurrence networks have small world effect. The small world effect shows that there is a short path between any two words in the four Mongolian word co-occurrence networks, and the connection between words is relatively close; The four networks have scale-free characteristics, which shows that in the four Mongolian word co-occurrence network, a few words have very many connections, while most words have only a few connections.