The invention provides a manufacturing method for an adjustable capacitor and the adjustable capacitor. The manufacturing method and the adjustable capacitor are applied to a performance test of an automobile ignition coil. The manufacturing method for the adjustable capacitor comprises the following steps: selecting the thickness of an intermediate dielectric layer according to the tested voltage of the adjustable capacitor and the breakdown strength of the intermediate dielectric layer; machining the intermediate dielectric layer to form a hollow cylinder body; arranging threads on the outer surface of the intermediate dielectric layer; selecting at least one cylindrical replaceable cushion block, and placing the at least one cylindrical replaceable cushion block in the intermediate dielectric layer, wherein the replaceable cushion block is made of dielectric material or metal material; placing an inner polar plate above the replaceable cushion block in the intermediate dielectric layer; performing threaded connection on an outer polar plate and the outer surface of the intermediate dielectric layer, wherein the outer polar plate can do spiral motion on the outer surface of the intermediate dielectric layer. The manufacturing method for the adjustable capacitor, provided by the invention, is simple in operation; the adjustable capacitor manufactured by the manufacturing method for the adjustable capacitor has the advantages of high voltage resistance, wide capacitance adjustment range and high adjustment precision.