The effects of the concentration of each component in the discharging agents composed of K CO and benzaldehyde sodium bisulfite(BASB) or Cleantex DSR(DSR) on the discharge of three vinylsulfonyl reactive dyes dyeing cotton fabrics were investigated. Whatever the discharging agents were composed of, 102$^{circ}C$$ imes$15 min steaming was much more effective on the discharge than 102$^{circ}C$$ imes$8 min steaming was. For the mixed discharging agents of K Co and BASB, the dischargeability improved as the concentration of K2c03 increased, but the effect of BASB was tiny. For the mixed discharging agents of K2c03 and DSR, the distinct improvement of dischargeability according to the increase of KBCOE or DSR was not shown since generally their dischargeabilities were good. Especially, the effect of K CO on the discharge of C.1. Reactive Blue 19(B-19) and C.1. Reactive Black 5(Bl-5) was profound. It was found that the discharge of B-19 which consists of anthraquinone was deeply affected by K CO, but, for that of C.1. Reactive Orange 16 of monoazo, DSR was very effective, and Bl-5 having two vinylsulfonyl groups and consisting of disazo was affected by both of K CO and BASB(or DSR).