In this paper, we prove a sharp and strong nonuniqueness for a class of weak solutions to the three-dimensional magnetohydrodynamic (MHD) system. More precisely, we show that any weak solution \((v,b)\in L^p_tL^{\infty }_x\) is nonunique in \(L^p_tL^{\infty }_x\) with \(1\le p<2\) , which reveals the strong nonuniqueness, and the sharpness in terms of the classical Ladyzhenskaya–Prodi–Serrin criteria at endpoint \((2, \infty )\) . Moreover, for any \(\epsilon >0\) , we can also construct infinitely many weak solutions of the ideal MHD system in \(L^1_tC^{1-\epsilon }_x\) . Our result shows the nonuniqueness for any weak solution (v, b) including nontrivial magnetic field b.
