The invention relates to the field of filters, and discloses a network filter and a manufacturing method thereof. In the network filter and the manufacturing method thereof which are provided by the invention, rib retaining walls are arranged on another two ends of a shell to facilitate weld penetration; copper wire wound iron cores are symmetrically arranged in a concave cavity, and varnish is filled on the surface of the concave cavity on which the copper wire wound iron cores are fixed so as to encapsulate the concave cavity; and copper wires with small diameters are adopted to wind small iron cores to ensure few crossings among wires, so the volume is reduced to adapt to the volume miniature developing tendency of the network filter. The distributed capacitance of the network filter is reduced by about 40 percent under the same condition by encapsulating the network filter with the varnish, the performance of the network filter is improved, the response time to network signals of the network filter is improved, the network transmission rate is improved, and the product yield is improved.