Modern complex circuits are described in very high speed integrated circuit hardware description language (VHDL) and difficult to verify. This paper proposes a systematic and visual dependency analysis method based on VHDL. The dependency relationships including control dependency, data dependency, signal control dependency and signal data dependency are defined. The entity dependency graph is presented and its generation algorithm, which searches the dependency relationships in hardware processes and between hardware processes, are developed. The experiment of a typical keyboard demonstrates that it is a visual and efficient method to analyze dependency relationships of VHDL for formal verification.