The assisting dyeing effects of RE in dyeing process of fur were systematically studied in this paper. The effects of the assisting dyeing, the dyeing-ratio, dyeing process-curve in dyeing process with RE to assisting dyeing were compared with those of normal dyeing process. The experimental results showed that RE can level dyeing process and increase dyeing-ratio. The goods dyed with RE to assisting dyeing have bright and full colour appearance. In addition, the proposal in using RE and another assisting-dyeing agent was advanced.