In this study, nitrogen-doped carbon dots (N-CDs) was observed to strongly amplify the chemiluminescence (CL) intensity of Ce (IV)-Na2S system with an enhancement factor around 55. Possible mechanism was explored and discussed on account of results of free radical scavenger experiments, CL spectra and X-ray photoelectron spectroscopy (XPS), etc. During the CL process, mono-dispersed N-CDs generated in situ catalyzed the production of more 1O2 on its surface and the CL enhancement mainly attributed to the chemiluminescence resonance energy transfer (CRET) between (1O2)2*/Ce (III)* and N-CDs. The new CL system was then developed as a convenient and sensitive platform for H2S detection. The linear range was 20–200 nM and the limit of detection (LOD) was 0.32 nM. The applications in different water samples were proved to have good recovery rate (tap water: 100.46%-109.22%; pool water: 99.91%-102.87%) with satisfactory results.