The dissociation dynamics of hydrogen molecular ions in intense fields has been investigated by using an accurate three-dimensional (3D) time-dependent wave packet approach. Its dissociation mechanism and intensity dependence can be studied by analyzing the dissociation probability and kinetic energy resolved (KER) spectra of H2+. It is found that the dissociation of H2+ comes from ν=5–9 states at the laser intensity of I1= 5.0×1013 W/cm2. The dissociation process includes bond softening (BS), bond hardening (BH), and below threshold dissociation (BTD). As the laser intensity increases to I2=1.0×1014 W/cm2, the above threshold dissociation (ATD) from ν=3 and 4 states is predominant, and the contributions from the bond softening and bond hardening are reduced during the dissociation process. The above conclusions may provide scientific prediction and theoretical guidance for the experiment in the future.