\documentclass[12pt]{article}

\usepackage{multibib}

\usepackage{CJK}
\newenvironment{Chinese}{%
  \CJKfamily{song}%
  \CJKtilde
  \CJKnospace}{}

\newcites{sec}{%
\begin{CJK*}{GBK}{}
\begin{Chinese}
{中国}
\end{Chinese}
\end{CJK*}
}

\begin{document}

We want to use the Chinese in the preamble for the multibib package.

\end{document} 