To check effects of operating variables on reaction characteristics of WGS catalyst for SEWGS process, water gas shift reaction tests were carried out in a pressurized fluidized bed reactor using ShiftMax210 catalyst and sand(as a substitute for $CO_2$ absorbent) as bed materials. Simulated syngas(mixed with $N_2$) was used as a reactant gas. Operating temperature was $210^{circ}C$ and operating pressure was 20 bar. WGS catalyst content, steam/CO ratio, gas velocity, and syngas concentration were considered as experimental variables. CO conversion increased as the catalyst content and steam/CO ratio increased. CO conversion at fluidized bed condition was higher than that of fixed bed condition. However, CO conversion were maintained almost same value within the fluidized bed condition. CO conversion decreased as the syngas concentration increased. The optimum operation condition was confirmed and long time water gas shift reaction test up to 24 hours at the optimum operating conditions was carried out.