Dual threshold voltage design is the most effective technique for reducing leakage current of integrated circuits. In this paper, we put forward an average leakage current macromodeling for dual-threshold circuits and propose two methods to conquer it, table-lookup based simulation and statistical analysis. The simulation is an efficient general-purposed method for leakage current estimation. For stochastic input circuits, a new statistical method is presented, which is much faster than the former one and can be used for very large circuits, because the method is based on input signal probability and only one pass of circuit is needed. To validate these two methods, accurate leakage currents are also calculated using popular simulator HSPICE for comparison. Experiments on ISCAS85 and ISCAS89 benchmarks demonstrate that the errors between them can be limited under 4% and thousand folds of time to results can be saved.