The dimension method and Π- theorem have been associated with experimental measurement to study the period revision for the transient process of a RLC electromagnetic vibration with a low damping degree.The first-order revision coefficient has been measured concretely and calculated accurately; and the second-order revision coefficient has been derived accurately and evaluated. The result is very well coincident with the approximate expansion of the strict vibration-period formula for the RLC transient process with a low damping degree.