\begin{figure}
\centering
\subfigure[]{
\begin{minipage}[b]{0.062\textwidth}
\includegraphics[width=1\textwidth]{u16.eps} \\includegraphics[width=1\textwidth]{P-16L.eps} \\includegraphics[width=1\textwidth]{R-16L.eps}
\end{minipage}
}
\subfigure[]{
\begin{minipage}[b]{0.062\textwidth}
\includegraphics[width=1\textwidth]{u32.eps} \\includegraphics[width=1\textwidth]{P-32L.eps} \\includegraphics[width=1\textwidth]{R-32L.eps}
\end{minipage}
}
\subfigure[]{
\begin{minipage}[b]{0.062\textwidth}
\includegraphics[width=1\textwidth]{u64.eps} \\includegraphics[width=1\textwidth]{P-64L.eps} \\includegraphics[width=1\textwidth]{R-64L.eps}
\end{minipage}
}
\subfigure[]{
\begin{minipage}[b]{0.062\textwidth}
\includegraphics[width=1\textwidth]{u96.eps} \\includegraphics[width=1\textwidth]{P-96L.eps} \\includegraphics[width=1\textwidth]{R-96L.eps}
\end{minipage}
}
\subfigure[]{
\begin{minipage}[b]{0.062\textwidth}
\includegraphics[width=1\textwidth]{u128.eps} \\includegraphics[width=1\textwidth]{P-128L.eps} \\includegraphics[width=1\textwidth]{R-128L.eps}
\end{minipage}
}
\subfigure[]{
\begin{minipage}[b]{0.062\textwidth}
\includegraphics[width=1\textwidth]{u200.eps} \\includegraphics[width=1\textwidth]{P-200L.eps} \\includegraphics[width=1\textwidth]{R-200L.eps} 
\end{minipage}
}
\end{figure}

Reference

[1].http://blog.sciencenet.cn/blog-561346-747243.html

minipage多列子图并列排版