In the H2SO4 medium and in the presence of dodecylbenzene sulfonic acid sodiumsalt (DBS), dimethyl yellow (R) could emit strong and stable solid substrate room temperature phosphorescence (RTF) on filter paper.And NaIO4 could oxidize R to cause the RTF quenching.Arsenic(V) could catalyze the reaction of NaIO4 oxidizing R, which caused the RTF sharply quenching.The reducing value of phosphorescence intensity (△Ip) for the system with DBS is 3.3 times higher than that without DBS.Moreover, the △Ip is proportional to the concentration of As(V).Based on the facts above, a new RTF quenching method for the determination of trace As(V) has been established.