A di- or triaziridinyl compound served as the latent curing agent for the prepared carboxylic groups containing aqueous-based polyurethane (PU) dispersions. It was formulated as a single pack self-curable aqueous-based PU system. This system was stable under an alkaline environment and its curing reaction could be initiated by a pH control. A model reaction between a monoaziridinyl compound and formic acid was demonstrated and identified by infrared spectrophotometry. The stabilities of this convenient one-package PU system with a different dosage of di- or triaziridinyl latent curing agent were monitored by a particle sizer and fluorescence spectroscopy. The PU films were cast and self-cured from these single pack PU dispersions at ambient temperature. The physical and mechanical properties as well as thermal behaviors of each self-cured PU were evaluated.