The　self-interference　digital　holographic　imaging　system　with　structured　light　illumination　is　developed　to　improve　the　axial　imaging　resolution　and　its　basic　principle　is　demonstrated.　The　numerical　simulation　and　experiment　arc　conducted　to　investigate　the　effects　of　the　spatial　frequency　of　the　structured　light　and　the　axial　distance　of　the　sample　on　the　tomographic　imaging　performances　of　the　system.　The　results　show　that　selfinterference　digital　holographic　imaging　under　structured　light　illumination　can　considerably　improve　the　tomographic　imaging　capability.