The experimental study on two-photon dissociation of HgI2 with a KrCl excimer laser at 222 nm is reported. Laser output at 5461 A(73S1-63P2）and 4358 A(73S1-63P1）from atomic Hg is obtained. The process of two-photon dissociation and the formation mechanism of the excited state Hg(73S1）are discussed.