A low threshold short cavity random distributed feedback fiber laser is designed.1455 nm laser diode is used as Raman pump and the length of dispersion compensating fiber is 7 km.The threshold is reduced to 760 mW and 520 mW by using forward feedback and backfeed configuration respectively.The second-order threshold of backfeed configuration is equal to the first-order threshold.The effects of dispersion compensating fiber length on laser threshold were analyzed.Experimental results show that the optimization of dispersion compensating fiber length is an effective method to reduce the first-order and second-order threshold.