In an ideal situation, good measuring system can be designed if exact information is known concerning performance and structures involved during the lifetime of the measuring object. But in the real world uncertainties of object exist in this information as well as in the method of measurement. To account for these uncertainties, concept of active measurement has been presented in this paper. Nowadays, scale transform and smart sensor have been applied for realizing elementary active measurement technique, the objective herein is to present measuring method of actively adjusting structure based on these factors. The practicality of this concept is illustrated with an engineering system using wire rope nondestructive testing device, double-point measurement device with eddy current probe as sensors is designed. Mathematical model of the rope’s characteristics and real-time quantity to trim of measure device is established according to relative spacing between sensors and rope. The idea of active control is introduced here, adjusting instrument structure timely based on mathematical relationships and feedback information will achieve the active measurement.