In this paper, cadmium sulfide (CdS) light emitting diodes (LED) die performance based on different structures configuration are simulated and investigated. The CdS LED extensively play an essential role in many applications, especially for the light sensor. The CdS LED die involves in this study are 10 μm height cylindrical circular, 9μm height dome-shaped, 10 μm height dome-shaped and 11 μm height dome-shaped structures. Increasing the height of the dome slightly changes the doping concentration and its ratio. Changes in the ratio of p-type and n-type affect the process recombination of electrons and holes. Thus, this produce high emission rate and optimum biased voltage. For the 10 μm height cylindrical circular structure, the threshold voltage of 1.95 V is recorded. Meanwhile, the 9μm height of domeshaped, 10μm height of dome-shaped and 11μm height of dome-shaped, the minimum voltage required to turn on the devices are 1.95 V, 1.96 V, and 1.975 V, respectively. It was found that dome-shaped with 11μm height generated the highest total emission rate for LED efficiency compared to other structures.