Two-dimensional (2D) perovskites for applications in photovoltaics and optoelectronics are attracting a great deal of research interest. The nonradiative electron-hole (e-h) recombination is the major efficiency loss channel. Herein, we report a study of the thickness dependence of the e-h recombination dynamics in diamine-based 2D perovskite via ab initio NAMD. For multilayer structures, due to the emergence of spontaneous interlayer electric polarization, which is induced by the collective and correlated reorientation of methylammonium molecules, the electron and hole at the band edges are localized in different inorganic layers, suppressing the e-h recombination. Furthermore, a broad range of phonon excitation also inspired rapid pure dephasing related to the microscopic origin for longer recombination times. The combination of the two effects leads to the observation of a prolonged carrier lifetime in multilayer 2D perovskites, which is essential to understanding the nonradiative e-h recombination mechanism in such materials.