Within the framework of the effective-mass approximation, the binding energy, optical transition energy, oscillator strength, and radiative lifetime of ionized donor bound exciton (D+X) in a Quantum Dot (QD) were calculated, assumed that the ionized donor was located at the disk axis, the disk-shaped QD consisted of a finite length cylinder of ZnO material surrounded by MgxZn1－xO. The calculations were performed by using a suitable variational wave function for finite confinement potential at all surfaces, including the strong built-in electric field effect due to the spontaneous and piezoelectric polarizations. Calculated results reveal that the disk structural parameters (height and Mg composition in the barrier) and the donor position have a strong influence on the binding energy, optical transition energy, oscillator strength, and radiative lifetime of (D+X) complex. As the disk height increases, the binding energy, optical transition energy, and oscillator strength both decrease, whereas the radiative lifetime increases. The influences of disk height on the binding energy, optical transition energy, oscillator strength, and radiative lifetime become more prominent for the QDs with higher Mg composition. The binding energy (the optical transition energy) has a maximum (minimum) when the donor is located in the vicinity of the left interface of the QDs. On the contrary, the binding energy (the optical transition energy) has a minimum (maximum) when the donor is located in the vicinity of the right interface of the QDs.