GaN-based green light emitting diodes was designed and fabricated. We calculated the internal electric field using the coupled method on the basis of analyzing the effect of the spontaneous polarization and the piezoelectric polarization. Taking into consideration of the effect of non-uniform carrier distribution in the active region, we obtained the fractions of the carriers and the rate of the recombination in different wells by calculating the steady state rate equation and Poisson equation. It was found that the calculation data are consistent with the experimental data for the changes of the peak wavelength, the light power and the halfwidth with the current in the range of 10—70 mA.