Ectomycorrhizal fungus has the ability to enhance the growth of higher plants in the contaminated area, especially ruined by heavy metals. And much attention was focused on how the fungus could enhance the resistance of higher plants. We focused on the resistance of ectomycorrhizal fungus in vitro to heavy metals. In the first experiment, the mycelium biomasses of two ectomycorhizal funguses growing in the Kottke media treated with different concentrations of Cu and Cd were measured after growth as well as the pH value of the medium. The results indicated that heavy metals could reduce the biomasses of the two funguses. Gomplhidius viscidus has higher tolerance to Cu but less Cd than that of Boletus edulis. With development of fungal mycila, the pH value of medium dropped significantly, and this effect might play an important role in enhancing its tolerance. In addition, the higher pH value change per biomass indicated that the fungus treated with heavy metals had the ability to adjust environment of pH more significantly. In the second experiment, the cation exchange capacity (CEC) of the cell walls of the fungus treated with heavy metals was measured according to Marschner's. The results indicated that with the increasing of the concentrations of Cu or Cd, the CEC of Gomphidius viscidus increased, but the CEC of Boletus edulis dropped.