Luminescent nanoclusters (NCs), with their easy preparation, ultrafine size, low toxicity, and excellent photostability have recently emerged as novel electrochemiluminescence (ECL) emitters. However, relatively low quantum yield (QY) in both aqueous and organic media has impeded their application in ECL emitter evolution. In this mini-review, we discuss the recent development of NCs in ECL with particular focus on their optical properties. We first classify the NCs according to composition and structure, and then summarize four aspects that affect QY, including environment effects, construction, valence state effects and aggregation-induced ECL. The ECL mechanisms based on NCs are elucidated as well. Finally, we briefly discuss the potential applications of NCs in tumor markers test, immunoassay and serum test. This review aims to provide a comprehensive summary of the progress of NCs in ECL, which will motivate researchers to develop NC chemistry and explore their future applications in ECL.