Recently,some studies demonstrated that neuron activity of the dorsal premotor cortex(PMd)showed selectivity for different hand gestures during planning period,which suggested that PMd is involved not only in arm reaching but also in hand grasping.However,it is difficult to identify whether the neuron selectivity results from visual cues related to object shapes or hand preshapes because different objects were asked to be grasped by using specific gestures in their experiments.In this study,we designed a free-choice task where a monkey was trained to autonomously choose one of two gestures(Power or Hook)to grasp the same object after a holding period for planning.Neural signals of PMd were collected by microelectrode array when the monkey was performing the task.With single unit activity analysis,we found that 18%(45/250)of units in PMd showed significant difference for the two gestures during movement planning period.In some of these units,the selectivity of their neuron activity disappeared immediately after the movement onset.We further examined the selectivity of neural activity on the neuron population level with a support vector machine(SVM)classifier.The gesture classification accuracy obtained from the neural activity of these tuning neuron subset could reach up to 93.5%during the planning period.Our results infer that the selectivity of partial PMd neurons during the planning period of grasp movements was closely related to the internal action selection or movement preparation rather than the external visual cues such as size or orientation of target objects.