Cello is a string instrument with a wide range of sound and rich expression. In order to achieve composer's creative ideas and performer’s personal interpretation, the process of pursuing tone color is endless. In this thesis, the first part we will start with the sound production of the string instrument in order to understand the foundation of the sound quality, and to explore different tone color by the bowing technique of the performer’s right hand, including the objective physical factors - the relationship between bow speed, bow pressure, contact point, and subjective physical sensation. In the second part, I will use Robert Schumann Five Pieces in Folk Style Op. 102 for Cello and Piano as an object to apply the results of previous research on the tone color of cello. In order to understand the psychological process behind Schumann’s composition, this thesis will also discuss his life and compositional background. Furthermore, the five distinctive pieces will be targeted as an object of performing practice.