The work is organized as follows: Chapter 1 presents an overview of the Cassini mission with particular focus on the Radio Science instrumentation and describes the current knowledge of the main satellites of Saturn whose gravity was analyzed in this work. Chapter 2 reviews the basic concepts of planetary geodesy and all the geophysical models used in the analysis. Chapter 3 is dedicated to the description of the mathematical formulation of the orbit determination problem. It includes a detailed description of the approach used and the data on which the analysis is based. Chapter 4 describes with more details the general characteristics of the analysis methods used to derive the geodesy of the main Saturnian satellites and includes the description of the dynamical model and all the key points of the analysis. Chapter 5 reports the results of the data analysis process with possible interpretations. Finally, Chapter 6 gives conclusions and future work perspectives.