This paper presents a novel method for automatic functional vectors generation from RT-Level HDL descriptions based on path coverage and constraint solving. Compared with existing method, the advantage of this method includes: 1) it avoids generating redundant constraints, which will accelerate the test generation process. 2) it solves the problem of how to propagate the internal values to the primary inputs with decision models. 3) it can handle various HDL description styles, and various styles of designs. Experimental results conduct on several practical designs show that our method can efficiently improve the functional vectors generation process. The prototype system has been applied to verify RTL description of a real 32-bits microprocessor core and complex bugs remained hidden in the RTL descriptions are detected.