Let \(A_{\pi }(n,1)\) be the (n, 1)-th Fourier coefficient of the Hecke-Maass cusp form \(\pi \) for \(\mathrm SL_3(\mathbb {Z})\) and \( \omega (x)\) be a smooth compactly supported function. In this paper, we prove a nontrivial upper bound for the sum \( \sum _{\begin{array}{c} n_1,\cdots ,n_\ell ,n_{\ell +1}\in \mathbb {Z}_+ \\ n=n_1^r+\cdots +n_{\ell }^r+n_{\ell +1}^s \end{array}} A_{\pi }(n,1)\omega \left( n/X\right) , \) where \(r\ge 2\) , \(s\ge 2\) and \(\ell \ge 2^{r-1}\) are integers.