A manufacturing method of an electronic device and an electronic device are provided. The manufacturing method includes the following steps: providing a substrate; forming a plurality of signal lines and a testing circuit on the substrate, wherein the testing circuit includes a plurality of output channels electrically connected to at least a portion of the plurality of signal lines; performing a testing process; and optionally isolating the testing circuit from the at least a portion of the plurality of signal lines. The testing process includes: providing a signal; processing a plurality of testing signals by processing the signal via the testing circuit; and transmitting the plurality of testing signals to the at least a portion of the plurality of signal lines via the plurality of output channels. The plurality of output channels are less than the plurality of signal lines in quantity.