Abstract: The technology of implementing Java with hardware （Java chip） is one of the most important directions of Java implementation technologies. Because of the virtualization of the Java virtual machine （JVM） instruction set, the current Java chips’ interface between software and hardware has to expand the instruction set. Such technology results in many shortcomings. In order to overcome these problems, a novel object oriented interface between software and hardware——Native Method Mapping——developed in a Java chip system is presented in this paper. Its implementation in the Java chip system is described in detail too. With this novel interface, the difficulties caused by the virtualization of JVM instruction set is solved, the development of operating system becomes easier, and the portability of the software is better.