Numbers of figure references

Question

I use enumerating of figures within the section

\renewcommand{\thefigure}{\arabic{section}.\arabic{figure}}

however, when I use a reference to subfigure, instead of 1.1 (a) I get 1(a). How should I fix it?

Working example

\documentclass{article}
\usepackage{amsmath}
\usepackage{subfigure}
\usepackage{graphicx}
\usepackage{caption}
\renewcommand{\thefigure}{\arabic{section}.\arabic{figure}}

\makeatletter
\renewcommand{\thesection}{\arabic{section}.}
\renewcommand{\thesubsection}{\thesection\arabic{subsection}.}

\renewcommand{\section}{%
    \@startsection
        {section}{1}{0mm}
    {\baselineskip}
    {\baselineskip}
     {\fontsize{14}{14}\centering\bfseries\MakeUppercase}%       
   }
   \makeatother

\begin{document}
    \section{a}
    \begin{figure}[h] \label{fig:1} \centering
        \subfigure[]{\label{fig:11}
            \includegraphics[width=60mm]{1.png}}%
        \subfigure[]{\label{fig:12}
            \includegraphics[width=60mm]{2.png}}

        \caption{11 and 12}.
    \end{figure}
    \section{b}
        \ref{fig:11}
\end{document}

Answer 1

Instead of using the obsolete subfigure package you should use subfig or subcaption; here's your code using subfig:

\documentclass{article}
\usepackage{amsmath}
\usepackage{subfig}
\usepackage[demo]{graphicx}
\usepackage{caption}

\renewcommand{\thesection}{\arabic{section}.}
\renewcommand{\thesubsection}{\thesection\arabic{subsection}.}
\renewcommand{\thefigure}{\arabic{section}.\arabic{figure}}

\makeatletter
\renewcommand{\section}{%
    \@startsection
        {section}{1}{0mm}
    {\baselineskip}
    {\baselineskip}
     {\fontsize{14}{14}\centering\bfseries\MakeUppercase}%       
   }
%subsection
\renewcommand{\subsection}{%
    \@startsection
    {subsection}{1}{0mm}
   {\baselineskip}
   {\baselineskip}
   {\fontsize{14}{14}\centering\bfseries\MakeUppercase}%
   }
\makeatother

\begin{document}

\section{a}
\begin{figure}[h] 
\centering
\subfloat[]{\label{fig:11}%
  \includegraphics[width=60mm]{1.png}}\ %
\subfloat[]{\label{fig:12}%
  \includegraphics[width=60mm]{2.png}}
\caption{11 and 12}
\label{fig:1} 
\end{figure}

\ref{fig:11} or \ref{fig:1}\subref{fig:11}

\end{document}

As a side note, your redefinition for \thefigure won't reset the counter when a new section begins; if you want to reset the counter you could use

\@addtoreset{figure}{section}

inside \makeatletter, \makeatother, or

\numberwithin{figure}{section}

from the amsmath package, or

\counterwithin{figure}{section}

from the chngcntr package. Also note that, inside floating environments, \label must always appear after \caption (in your code \label is before \caption).

If, for some reason you need to stick to the subfigure package, then you can redefine \thesubfigure, \p@subfigure, and \@thesubfigure:

\documentclass{article}
\usepackage{amsmath}
\usepackage{subfigure}
\usepackage[demo]{graphicx}
\usepackage{caption}

\renewcommand{\thesection}{\arabic{section}.}
\renewcommand{\thesubsection}{\thesection\arabic{subsection}.}
\renewcommand{\thefigure}{\arabic{section}.\arabic{figure}}
\renewcommand{\thesubfigure}{\thefigure(\alph{subfigure})}
\makeatletter
\renewcommand{\p@subfigure}{}
\renewcommand{\@thesubfigure}{(\alph{subfigure})\hskip\subfiglabelskip}
\makeatother

\makeatletter
\renewcommand{\section}{%
    \@startsection
        {section}{1}{0mm}
    {\baselineskip}
    {\baselineskip}
     {\fontsize{14}{14}\centering\bfseries\MakeUppercase}%       
   }
%subsection
\renewcommand{\subsection}{%
    \@startsection
    {subsection}{1}{0mm}
   {\baselineskip}
   {\baselineskip}
   {\fontsize{14}{14}\centering\bfseries\MakeUppercase}%
   }
\makeatother

\begin{document}

\section{a}
\begin{figure}[h] 
\centering
\subfigure[]{\label{fig:11}%
  \includegraphics[width=60mm]{1.png}}\ %
\subfigure[]{\label{fig:12}%
  \includegraphics[width=60mm]{2.png}}
\caption{11 and 12}
\label{fig:1} 
\end{figure}

\ref{fig:11}

\end{document}