Abstract: VHDL-AMS language provides a behavioral level modeling and simulation method for the design of analog and mixed-signal system. This paper introduces the modeling characteristics supported by VHDL-AMS and basic syntax elements of the language, analyzes some issues about modeling method of analog and mixed-signal system based on VHDL-AMS, including conservative system and signal flow modeling mode for analog system, corresponding relationship between system equations and variables, and mixed-signal mechanism. Finally the paper analyzes and validates the function of the language and the presented modeling method through three examples.