Abstract: Coal，slag，limestone，water in desulfurization process，gypsum，desulfurization wastewater and ash were sampled and tested in order to study mercury emission characteristics from a typical coal-fired power plant． EPA30B and Ontario-Hydro methods were applied to determine the mercury speciation of flue gas in different position． The results indicated that the mercury emission concentration of 300 MW unit met“Emission Standard of Air Pollutants for Thermal Power Plants”( GB 13223—2011) ． The mercury emission in flue gas accounted for a considerable proportion，reaching 89. 50%，and the amount of mercury emission into the atmosphere was about 38. 72 μ g / ( kW·h) ． The flue gas purification system of typical 300MW units was SCR + ESP + WFGD combined process，and the removal efficiency of mercury in flue gas was only 29. 71%，and mercury removal rate was not high without strengthen the mercury removal measures．