Via molecular dynamics simulations employing an embedded-atom-method potential, we investigate the microscopic process and dynamical properties of shock-induced micro-jet from a grooved aluminum surface. For a large range of shock pressure, we obtain the micro-jet morphology variation, its mass spatial distribution and mass-velocity distribution. The amorphous state and release melting during the jetting are both analyzed using the central symmetry parameter, where the effect law of release melting on the micro-jet is obtained. It is found that the micro-jet mass keeps a linear increase with the piston velocity prior to release melting; the micro-jet mass is enhanced evidently after release melting; while the velocity of release melting is above a threshold, the jetting mass shows a linear increase with the piston velocity again, where the strength of material can be neglected.