Abstract: Based on the stochastic theory, we consider the calculation of the delay of multi-terminal interconnect nets with random walk based capacitance extraction. An adaptive accuracy-guaranteed method for calculating the interconnect delay has been proposed. In this work, the relationship between the stochastic errors of interconnect delay and the stochastic errors of capacitances due to random walk algorithm has been derived, resulting to a theoretical upper bound of delay error. Then, two adaptive strategies are proposed for the accuracy-guaranteed delay calculation. One is based on the upper bound of delay error, and the other is based on an error fine-tuning approach. The method automatically adjusts the error threshold and the time of running the random walk based capacitance extraction, and employs a restoring extraction technique to largely reduce the runtime. The experimental results on interconnect structures from actual circuit layouts show that, the proposed method is able to guarantee the accuracy of calculated delay. And, the approach based on error fine-tuning is more efficient than the approach based on upper bound estimation of the delay error. The former reduces the total runtime including that for capacitance extraction to a small quantity while guaranteeing the stochastic delay error.