Recently, as the resolution of the display being released increases, interest in quantum dots (QDs) with particle size of a few nanometers is increasing. QDs are regarded as a material for next-generation displays based on various characteristics like optical, magnetic property and high color reproducibility. Among others, blue emitting quantum dots have get a lot of attention due to light-emitting devices. In order to realize QLED that is perfectly self-luminous format, so essential that blue QDs develop. The development of the QDs of the Cd-free is necessary because the Cd used as the basis for many groups to implement blue QDs is toxic. We achieved emissions of 440-450 nm by repeatedly using the SILAR method, which involves alternate addition of cations and anions. To improve the quantum yield, we performed repeated ZnS coating. Finally, we used halide anion to conduct surface passivation and get a very efficient blue QDs and a maximum quantum yield of 64.0%. This is the highest yield reported for ZnSe/ZnS QDs in the 440-450nm range.