In this paper, a kind ofmicrowave-discharge pumped cw atomic mercury laser is introduced and demonstrated. In thisexperiment the laser is put in a microwave-guide, laser light is produced by means ofmicrowave discharge. Whole dielectric medium, inner-cavity style, and co-axial structureare employed. 80 W microwave power is input in the microwave-guide, 30 W power is absorbedby the mercury medium. Laser cavity consists of 2 m spherical radius mirrors withreflectance of 99.9%. Laser wavelength is 546.1 nm and its maximal power output is 0.1 mW.Light spot size is 3 mm with several transverse modes.