With the increase of integration level and operation frequency of electronic devices and systems, packages are having much more impact on signal integrity issues.So getting the accurate electrical model of the package is becoming more and more important for IC system designers.The Ceramic Ball Grid Array or CBGA package, is a promising choice for high speed digital applications such as CPU, DSP and FPGA and so on.Excellent attributes of this advanced package include miniaturized footprint, good electrical performance and excellent thermal characteristics.This paper is based on CBGA500 package, designed by the package center of Beijing Microelectronics technology institute, the wideband electrical parameters of one signal path for a typical 500 I/O (1.0 mm pitch) CBGA package structure, were modeled precisely using EM simulation software Ansoft HFSS and ADS of the Agilent company.The simulation result shows the electrical parameter model we got can characterize the selected signal path very well from 0 to 350MHz, and the Scatting parameter difference between the wideband model and the HFSS model is less than 5 percent.So using this method, we can get very accurate electrical model of packages, which means a lot for system designers.