Five-axis turning-milling center is an important and advanced NC machine in fields of military industry, aerospace, automobile and medical machinery. The kinematics equation is built based on D-H method by the analysis of the structure of five-axis turning-milling center. The precision workspace is presented and its definition is given. The precision workspace of five-axis turning-milling center is analyzed based on Monte Carlo method. The mathematical model of precision reliability for machining center is built. The sensitivity of precision reliability for machining center is analyzed using analytical method. Finally, sensitivity histograms are given.