In the high-level synthesis of application-specific DSP, pipeline scheduling is a difficult and urgent problem Concerning the global optimization of functional units, registers and interconnections, we present a novel algorithm called directed searching pipeline scheduling, which is an iterative algorithm utilizing heuristic information. The heuristic information speeds up the searching process, and the weakness of deterministic algorithms, which are vulnerable to trip in local optimal, poor at hill-climbing, is overcome in this algorithm. Typical design examples show that the performance of this transformation-based algorithm has reached or surpassed the best performance of pipeline scheduling algorithms reported so far.