Abstract: An analytical method to evaluate time zones of interference for a dual-arm robot is presented with the con-sideration of shape and volume of links in the case,when the robot arms move along two given continuoustrajectories in three dimensional space respectively.A simplified model of links is given.The formulationsand criteria to determine interference zones are derived.The method is applicable to general dual-arm robotswith not only revolute joints,but also prismatic joints.A numerical example is presented for illustration.