The invention discloses a thermosetting manufacturing method of a flexible circuit board. The thermosetting manufacturing method includes the steps of A, using a cutting machine to cut a copper sheetinto a set-size and set-shape base material; B, using an exposure development itching method to form a circuit on the surface of the base material; C, using a drilling machine to automatically drill positioning holes in the base material; performing solder resist pretreatment; E, performing solder resist silk-screen printing, to be more specific, using ink and a silk-screen printing method to print characters on the surface of the base material; F, using a baking oven to perform solder resist baking; G, inspecting whether the product is qualified or not. The thermosetting manufacturing methodis few in procedures, low in cost and high in production efficiency.