In order to explain the phenomena of negative capacitance(NC) in light-emitting diodes(LEDs),we presented a new model based upon the local strong recombination in active region.And we deduced the analytic expression of NC from continuity equation.The theoretical result shows that the NC effect becomes stronger when the carries recombination rate,for a certain range,increases.And it consists with the experimental result.Accordingly,we confirm that the NC is caused by carries recombination in active region instead of by other exterior factors.