Abstract: A self-consistent field theory (SCFT) for polydisperse polymers grafted to a surface was developed. By solving the resulting equations numerically, both density profiles and free end distributions for bidisperse polymers consisting of two different chain lengths were simulated with moderate to strong excluded volume interactions. The results showed that the monolayer of bidisperse polymers separated into two sublayers as excluded volume interactions increased. The density profiles simulated by the self-consistent field theory were consistent with the results of the strong stretching theory when excluded-volume interactions were high. Also the free end distributions of long chains were close to the prediction of strong-stretching theory(SST)in that case. But the free end distributions of short chains deviated from the SST results evidently. The average trajectories for both short and long chains were calculated. It revealed that short chains in bidisperse polymers were less stretching than the monodisperse chains with the same chain length. However long chains in bidisperse polymers were more stretching than the monodisperse chains with the same chain length in the inner layer and less stretching than that in the outer layer.