Chinese and English are mixed in WinEdt:

\documentclass[UTF8]{ctexart}
\begin{document}
中文中文English
\end{document}

The following two problems have occurred with PDFTeXify:

! Package inputenc Error: Keyboard character used is undefined
(inputenc)                in inputencoding `utf8'.

and

! Package CJK Error: Invalid character code.

Solution: [WinEdt]-& GT; [Document]-> [Document Settings]-> The Format to utf-8