Radio frequency plasma was used to prepare a vanadium catalyst. The results showed that activating time of the catalyst could be shortened quickly and the catalytic activity was improved to some extent with the use of plasma. Catalyst Ls-9 was prepared under an optimal condition of 40 W discharge power, 10 min discharge time and 8 Pa gas pressure. The catalytic activity was up to 54.7% at 410 ℃,which was 2.2% higher than that of the Ls-8 catalyst. Only 10 min was needed to activate the catalyst with plasma, which was 1/9 of the traditional calcination time. For Ls-9, both the endothermic as well as the exothermic peaks detected by differential thermal analysis shifted to higher temperatures obviously,indicating that its crystal phase could melt easily. There existed an apparent endothermic peak at 283 ℃. SEM photographs showed a uniform size distribution. It is inferred that the quadrivalent vanadium compound may exist mainly in the form of VOSO4.