We study the thermal characters of the inner horizon of a Gibbons-Maeda black hole.In order to satisfy the Nest theorem of the third law,the entropy of the black hole with two horizons must depend not only on the area of the outer horizon but also on the area of the inner horizon.Then the temperature of the inner horizon is calculated.Lastly,the tunnelling effect including the inner horizon of a Gibbons-Maeda black hole is investigated.loss.