The interaction between light and atom can be described by the theory o f density matrix equations.Based on the theory,the absorption of Rydberg atom under the driven of two laser fiel ds is simulated analytically,where a model of ladder type three-level system is adopted.It is found that probe abso rption presents resonant enhancement only when the intensity of the coupling and probe field is smaller than the crit ical value.The magnitude of the absorption peak increases with the increase of laser intensity,until to the max imum value.Just then,the intensity of the laser field equals the critical value.The line-width of absorption increas es with the intensity of probe field, while it is independent of the coupling one.After the intensity is larger than the critical value,the absorption peak decrease and develop into a structure of double peaks with the increase of inten sity.The interval between two peaks increases with the enhancement of the field,which is attributed to the splittin g of energy level caused by the strong field.The interval of the splitting energy level increases with laser intensity .The position of two peaks is different from the one of EIT system,which is at.With the enhancement of coupling field, two peaks are more and more close to the position of.It is also found that as the probe field is w eak,the magnitude of two peaks increases slowly with the increase of the coupling field,while it will de creases gradually as the probe field is strong.