A comprehensive understanding of the complex physical and chemical process involved in the dissociation process of energetic materials is essential for laser initiation. In this paper, experimental investigations were carried on to reveal the dissociation mechanism of 2,2′,4,4′,6,6′-hexanitrostilbene (HNS) under 1064nm excitation. The positive and negative ions produced in the laser-induced dissociation processes were detected by a time of flight mass spectrometer (TOFMS) in vacuum (4×10-4 Pa). By analyzing the molecular structure of HNS and mass to charge ratio (m/z), possible attributions of different ions were obtained. For the negative ions, the dominant peak appeared at m/z=26, 42, 50, 74, 100 and 136, which corresponded to CN, CH2N2/C2H2O/CNO, CHCCHC, C6H2, C6H2CN and C6H2ONO2. For the positive ions, the main peaks could be found at m/z= 24, 28, and 40, these peaks could be ascribed to C2, CO/N2/CH2N and CH2CN. The intensity of the ion fragments increased gradually with the increasing of laser fluence. The relationship between the ion intensity and the delay time was also revealed. The results might give some help for the further understanding of the laser initiation process of HNS.