Input Buffered switches can not directly deal with variable size packets. The variable length packets need to be segmented into fixed length cells before scheduling. Then segmentation and reassembly (SAR) must be used. The traditional SAR scheme can lead to significant loss of fabric bandwidth due to the padding bytes, which requires speed up in switch fabric to compensate for this bandwidth loss. The improved scheme called cell merging can reduce the bandwidth loss greatly but it has low scalability and it is difficult to select suitable merging size. In this paper, we propose a new method of SAR for Input buffered switches using the queue information of switches and can adjust the segment size dynamically. New scheme is suitable for different traffic model and can provide an excellent delay performance. We evaluate DSAR scheme using simulation, the results show that it outperforms existing segmentation schemes in Input Buffered switches.