Abstract: In this work, we used time-sliced ion velocity imaging to study the photodissociation dynamics of MgO at \mbox193 nm. Three dissociation pathways are found through the speed and angular distributions of magnesium. One pathway is the one-photon excitation of MgO(X^1\Sigma^+) to MgO(G^1\Pi) followed by spin-orbit coupling between the G^1\Pi, 3^3\Pi and 1^5\Pi states, and finally dissociated to the Mg(^3P_\textrmu)+O(^3P_\textrmg) along the 1^5\Pi surface. The other two pathways are one-photon absorption of MgO(A^1\Pi) state to MgO(G^1\Pi) and MgO(4^1\Pi) state to dissociate into Mg(^3P_\textrmu)+O(^3P_\textrmg) and Mg(^1S_\textrmg)+O(^1S_\textrmg), respectively. The anisotropy parameters of the dissociation pathways are related to the lifetime of the vibrational energy levels and the coupling of rotational and vibronic spin-orbit states. The total kinetic energy analysis gives D_0(Mg-O)=21645\pm50 cm^-1.