The present disclosure provides II-VI based non-Cd visible light emitting quantum dots (QDs) and a manufacturing method thereof to solve the problems with broad full width at half maximum (FWHM) and low quantum efficiency. The present disclosure further provides a QD light emitting diode (QLED) using the II-VI based non-Cd visible light emitting QDs. The QDs according to the present disclosure include a II-VI based ternary ZnSeTe core, wherein a Se:Te ratio in the ZnSeTe core is 1:10 to 100:1. According to the present disclosure, it is possible to provide QDs that emit visible light ranging from red to blue by adjusting the Se:Te ratio in the II-VI based ternary ZnSeTe core.