Abstract: With the influence of various complex factors in actual manufacturing and working process,post-silicon critical paths of integrated circuit would have uncertain change.It makes large deviation of pre-silicon timing analysis and is hard to guarantee the correspondence between pre and post-silicon.A novel pulse flip-flop based circuit structure to detect critical path is proposed in this work.By reusing the redundant latch as a shadow latch and inserting additional propagation delay at its data input,the two latches would have different setup timing margin;then the critical paths were detected by comparing the difference between the sampling values of two latches.The HSPICE simulation results show that the proposed design not only realized the basic function of pulse flip-flop but also could detect the critical path effectively.It has smaller area overhead and significant power optimization compared with other structures.Finally,its integration process has been presented to applicate the circuit in actual physical design.