Recent studies have demonstrated that the androgen receptor (AR) could play important roles to promote renal cell carcinoma (RCC) cell proliferation, and other studies have also indicated that suppressing the argininosuccinate synthase 1 (ASS1) could promote proliferation of various tumors. The potential of AR promoting cell proliferation in RCC via altering ASS1, however, remains unclear. Here we found that the expression of ASS1 was lower in RCC tissues than in adjacent normal renal tissues, and a lower ASS1 expression was linked to a worse prognosis in RCC patients. Mechanism dissection showed that AR could decrease ASS1 expression to promote RCC cell proliferation via ASS1P3, a pseudogene of ASS1. The results of RIP assay and AGO2 assay revealed that AR could bind ASS1P3 to increase RCC cell proliferation via altering miR-34a-5p function, which could bind to the 3'UTR of ASS1 to suppress its protein expression. ASS1P3 could function as a miRNA decoy for miR-34a-5p to regulate ASS1 in RCC. Preclinical study also supports the in vitro data. Together, these results demonstrated that ASS1P3 could function as a competing endogenous RNA to suppress RCC cell progression, and targeting this newly identified AR-mediated ASS1P3/miR-34a-5p/ASS1 signaling might help in blocking proliferation.