A modified matrix enhancement and matrix pencil (MMEMP) method is presented for the scattering centers measurements in step-frequency radar. The method estimates the signal parameter pairs directly unlike the matrix enhancement and matrix pencil (MEMP) method which contains an additional step to pair the parameters related to each dimension. The downrange and crossrange expressions of the scattering centers are deduced, as well as the range ambiguities, from the point of view of MMEMP method. Compared with the Fourier transform method, the numerical simulation shows that both the resolution and precision of the MMEMP method are higher than those of the Fourier method. The processing results of the real measured data for three cylinders prove the above conclusions further.