It seems that the best solution is to remove xlabel and use xscale label instead. My solution is posted below:
\documentclass{article}\usepackage{pgfplots}\pgfplotsset{compat=1.14}\begin{document} \begin{tikzpicture} \begin{axis}[ scaled x ticks=true, scaled y ticks = false, y tick label style={/pgf/number format/fixed}, xtick scale label code/.code={$x$ $ ( 10^{#1}$ m)}, xlabel = {}, ylabel = {$ y $}, ] \addplot[line width=3pt] coordinates {(0.0,0.0)(100,1)(400,2)(10000,0)}; \end{axis} \end{tikzpicture}\end{document}