Abstract: This paper considers Wilcoxon signed rank test based on the median ranked set sample. For any fixed set size in the proposed sampling the asymptotic distribution-free of the test statistic is established. Then, it is proofed analytically the Pitman efficacy of the Wilcoxon signed rank test under the median ranked set sampling is not only higher than that under the simple random sampling but also superior to the sign test under the median ranked set sampling.