The invention relates to a biodegradable nerve conduit with a bilayer structure and a preparation method thereof. The biodegradable nerve conduit comprises a reticular monofilament liner which is made of polyglycollide-lactide (PLGA) and used as a framework structure and a nano fiber felt which is made of a biodegradable material and used as an outer layer structure. The preparation method comprises the following steps of: (1) preparing PLGA monofilaments by adopting a fused spinning method, stretching for orientating, and then weaving into a reticular liner conduit; (2) dissolving the biodegradable material into an organic solvent to prepare a spinning stock solution with a mass fraction of 3-20 percent; and (3) carrying out electrostatic spinning by using the spinning stock solution on the surface of the reticular liner conduit by taking the reticular liner conduit as a receiving device to obtain the biodegradable nerve conduit. The biodegradable nerve conduit has good biocompatibility, proper degradation time and higher mechanical strength and can promote the regeneration and the restoration of damaged nerves. The preparation method has the advantages of simpleness of operation, low cost, environmental protection, high economic benefit and good application prospect.