Abstract Introduction Controlling the pain after TKA has always been our research focus. Dexamethasone has a significant effect in controlling acute pain following TKA. We hypothesis oral administration of prednisone could alleviate post-TKA subacute pain. Methods This was a prospective, randomized controlled trial dividing patients into prednisone group and control group. Routine analgesic regimens included injection of cocktail mixture intraoperatively, oral celecoxib and tramadol postoperatively. Patients in prednisone group received oral administration of prednisone (10 mg, qd, from the first day postoperatively, for 2 weeks). VAS was applied for evaluating pain with ambulation (PWA) and pain at rest (PAR). Follow-up was performed for about three months. The primary end-points were PWA and PAR; secondary end-points were postoperative daily celecoxib use and tramadol use. Results A total of 49 patients were enrolled in prednisone group and control group, respectively. VAS of PWA was lower in prednisone group on the 7th, 14th and 28th (p = 0.05) day after TKA than that in the control group. Meanwhile, VAS of PAR was lower in prednisone group on the postoperative 14th and 28th day (p = 0.05) than that in the control group. Conclusions Continuous oral administration of 10 mg prednisone for 14 days after TKA effectively alleviates subacute pain (including PWA and PAR) and reduces postoperative consumption of analgesics. Level of evidence II; low power randomized trial.