The composite soil-nailing has been wildly used in the soft soil zone, but its theory for design and calculation cannot satisfy the present project application. With the aid of the non-linear plane strain finite-element, the distortion performance of composite soil-nailing during the step-by-step excavation and supporting process was studied. Through the contrast testing with engineering examples, the rationality of this method was verified. The preliminary view to the composite soil-nailing design was proposed.