An adjustable reactor and an equal-step adjustment method therefor, which relate to the technical field of electronic testing, and solve the technical problem of how to provide a reactor that has a wide adjustment range and that can be digitally controlled. The adjustable reactor comprises a first adjustable inductance unit, a second adjustable inductance unit, ...and an n-th adjustable inductance unit. The first adjustable inductance unit, the second adjustable inductance unit, ...and the n-th adjustable inductance unit form a successive series connection; any one adjustable inductance unit among the first to the n-th comprises a composite inductor and a single-pole multi-throw switch; and the composite inductor is connected to the single-pole multi-throw switch. The equal-step adjustment method comprises: step one, listing a matrix of values of single inductances of an adjustable induction unit; step two, normalizing the matrix of values of single inductances of the adjustable inductance unit; and step three, performing equal-step adjustment.