Co-occurrence networks of Chinese characters are constructed from collections of essays in different periods of China:the ancient Chinese language,the Chinese language in Wei,Jin,and Southern-Northern Dynasties,the recent Chinese language,and the modern Chinese language,and their statistical parameters are studied.It has been found that 99.6% networks have the scale-free feature and 95.0% networks have the smallworld e?ect.This study reveals some commonalities and di?erences among articles in different periods of China from a complex network perspective.There has been a controversial question as to whether the literatures in Wei,Jin,and Southern-Northern Dynasties should belong to the ancient Chinese language or the recent Chinese language in the linguistic study.Our work shows that the statistical parameters of networks in Wei,Jin,and Southern-Northern Dynasties are clearly different from those of networks in the other periods of China,and it seems more reasonable that the literatures in Wei,Jin,and Southern-Northern Dynasties belong to the recent Chinese language.