We report on a systematic investigation of the dissociation dynamics of H2+ in intense laser fields, and study how the kinetic energy spectrum of the dissociating proton can be modulated by the wavelength and intensity of the driving laser field. In the experiment, H2 is dissociatively ionized by an intense laser pulse with varying carrier wavelengths ranging from 800 to 1800 nm and varying peak intensities. A model based on Floquet theory and Landau-Zener theory is adopted to explain the experimental observations. The intensity effect is further explored in a few-cycle pump-probe experiment. We observed a significant intensity-dependent proton kinetic energy shift, which can also be well explained by the theoretical simulation. The wavelength- and intensity-dependent proton spectra reveal the mechanism of selective excitation of vibrational levels of H2+ in intense laser fields.