Objective To explore the role of excitatory amino acid carrier 1 (EAAC1)in dorsal root ganglion (DRG) in the mechanism of developing morphine tolerance. Methods Thirty male SD rats were implanted intrathecal catheters and randomized into 6 groups with 5 rats each. The rats of 4 groups were made into the model of adjuvant-induced arthritis in the left hind limb and were administered intrathecally, morphine 10 μg(group M_(10)), morphine 20μg(group M_(20)), morphine 20 μg plus naloxone 10 μg(group MN) ,or saline(group C) respectively. The other 2 groups without were administered intrathecally saline (group C_0) or morphine 20 μg (group M0). The drugs were administered twice daily for 7 days. Mechanical withdrawl threshold(MWT) of the left hind limb was examined to evaluate the behavior. Immunohistochemistry was used to detect the expression of EAAC1 in the left L_(3-4) and L_(4-5) DRG. Results Morphine tolerance was formmed stably in the arthritis rats of group M_(10) and group M_(20) after administering morphine for 7 days. The expression of EAAC1 in DRG was downregulated. Conclusion DRG EAAC1 may be involved in the mechanism of developing morphine tolerance in rats with inflammatory pain.