An analytical form of the e+e- annihilation cross section including initial-state radiation near the Z is presented. Its accuracy is 0.1% within (M -3-GAMMA-Z,M + 2-GAMMA-Z) and 0.4% within (M -4-GAMMA-Z,M + 4-GAMMA-Z) for the lepton as well as hadron channels. The formulas could be used to extract the physical parameters of the Z boson from the data of e+e- colliding experiments.