In this paper, we have reported a mixing alkali medium method for the preparation of highly emissive CdTe quantum dots (QDs). The pH of the reaction medium was tuned by varying the ratio of ammonia and sodium hydroxide, and the photoluminescence quantum yield of the as-prepared CdTe QDs was greatly enhanced compared to the traditional single alkali source method. Due to the good photoluminescence, the as-prepared CdTe QDs possess high potential in cell imaging.