Abstract: In this paper we describe the architecture of the 3D graphics LSI core for mobile phone "Z3D." The major 3D graphics applications on mobile phones are character animation and games. While a character animation or a game is running, the CPU has to be used for the communication to the center machine and CPU clock frequency is low. Therefore, the requirement of Z3D is small, low power, and CPU free. The pipeline of Z3D is composed of a geometry engine, rendering engine, and pixel engine. Generally, these modules run in pipeline on PC, but running in pipeline, power consumption rises. We used gated clock control for low power consumption and having the pipeline work in sequential, we could reduce 40% of the power consumption with 10% performance decreasing. The geometry processing performance of Z3D is up to 185K vertex/sec and the pixel performance is 5Mpixel/sec. This performance is enough to have character animations and games run. The data of 3D shape and animation can be defined using common 3D modeler and contents program can be described by Java. Low level rendering interface and animation rendering interface are provided as a Java API. All the contents programs can be downloaded from network.