Let \(M_1\) , \(\cdots \) , \(M_\ell \) be complete, connected and non-collapsed manifolds of the same dimension, where \(2\le \ell \in \mathbb {N}\) , and suppose that each \(M_i\) satisfies a doubling condition and a Gaussian upper bound for the heat kernel. If each manifold \(M_i\) has volume growth either bigger than two or equal to two, then we show that the Riesz transform \(\nabla {\mathscr {L}}^{-1/2}\) is bounded on \(L^p(M)\) for each \(1<p<2\) on the gluing manifold \(M=M_1\#M_2\#\cdots \# M_\ell .\)