<p style='text-indent:20px;'>In this paper, we investigate the nonnegative solutions of the nonlinear singular integral system</p><p style='text-indent:20px;'><disp-formula> <label/> <tex-math id="FE1"> \begin{document}$ \begin{equation} \left\{ \begin{array}{lll} u_i(x) = \int_{\mathbb{R}^n}\frac{1}{|x-y|^{n-\alpha}|y|^{a_i}}f_i(u(y))dy,\quad x\in\mathbb{R}^n,\quad i = 1,2\cdots,m,\\ 0<\alpha<n,\quad u(x) = (u_1(x),\cdots,u_m(x)),\nonumber \end{array}\right. \end{equation} $\end{document} </tex-math></disp-formula></p><p style='text-indent:20px;'>where <inline-formula><tex-math id="M1">\begin{document}$ 0<a_i/2<\alpha $\end{document}</tex-math></inline-formula>, <inline-formula><tex-math id="M2">\begin{document}$ f_i(u) $\end{document}</tex-math></inline-formula>, <inline-formula><tex-math id="M3">\begin{document}$ 1\leq i\leq m $\end{document}</tex-math></inline-formula>, are real-valued functions, nonnegative and monotone nondecreasing with respect to the independent variables <inline-formula><tex-math id="M4">\begin{document}$ u_1 $\end{document}</tex-math></inline-formula>, <inline-formula><tex-math id="M5">\begin{document}$ u_2 $\end{document}</tex-math></inline-formula>, <inline-formula><tex-math id="M6">\begin{document}$ \cdots $\end{document}</tex-math></inline-formula>, <inline-formula><tex-math id="M7">\begin{document}$ u_m $\end{document}</tex-math></inline-formula>. By the method of moving planes in integral forms, we show that the nonnegative solution <inline-formula><tex-math id="M8">\begin{document}$ u = (u_1,u_2,\cdots,u_m) $\end{document}</tex-math></inline-formula> is radially symmetric when <inline-formula><tex-math id="M9">\begin{document}$ f_i $\end{document}</tex-math></inline-formula> satisfies some monotonicity condition.</p>