A manufacturing method of a circuit board and a display device are provided. In the method, an error caused by that pin alignment on a conventional flexible substrate after a pin column is disposed on the flexible substrate based on a second pin position and a hot pressing process is performed is adjusted, so that the pin alignment is more accurate after the flexible substrate on which a pin is disposed based on a position of the to-be-disposed pin column is finally hot pressed with the display panel, thereby avoiding a problem that the pin is misplaced or short-circuited, and improving a good rate of the product.