In this work, a polarization-resolved electrochemiluminescence (ECL) sensor for microRNA-155 (miRNA-155) detection has been constructed based on the surface plasmon coupling effect. In the sensing system, nitrogen dots (N dots) were employed as ECL emitters. As a surface-enhanced structure, a gold nanorod vertical array was constructed on the electrode surface by the volatilization-induced self-assembly. The coupling of the adjacent gold nanorods in the array can generate significant local electromagnetic fields. Due to the anisotropy of gold nanorods and the hot spot effect of the vertical array, the ECL signal of N dots was greatly improved at a specific polarization angle. In addition, the catalytic hairpin self-assembly strategy was used to amplify the nucleic acid analyte signal. As a result, the polarization-resolved ECL sensor can detect miRNA-155 sensitively, which is related to triple-negative breast cancer.