The microcavityefficiently enhancement of organic electroluminescent devices was investigated, thedevices is consisted of the hole transporter ladder-type poly (p-phenylene) and theelectron transporter 8-hydroxyquinoline aluminum with dye pyrromethene-doping. Themicrocavity effect could be achieved by adjusting organic layer thickness between Al andITO electrode. The results obtained showed that the microcavity electroluminescenceefficiency was greatly enhanced.