The interval Newton (IN) method is one of the methods which are capable of finding all solutions of a system of nonlinear equations. Many approaches have been proposed to improve the efficiency of the method when applying to problem of finding all direct current (DC) solutions of nonlinear circuits. The IN method consists of many steps, one of them is the box-splitting. This is usually performed by splitting the box in some appropriately chosen coordinate direction to form two new smaller boxes. In this paper, a simple box-splitting strategy is proposed when the IN method is applied to find all DC solutions of a circuit whose nonlinear elements are only diodes and bipolar junction transistors. The idea is to employ the voltage-current characteristic of diode to find the appropriate splitting point. The proposed technique has been implemented using C-XSC toolbox. Its performance is evaluated by testing with some test nonlinear circuits. The results indicate that the proposed technique can reduce the number of search boxes and improve the computation time.