In this work, a novel aluminum metal-organic framework (Al-MOF)/N-2-hydroxyethylpiperazine-N'-ethane-sulfonic acid (HEPES) system with an excellent electrochemiluminescence (ECL) property was developed. First, Al-MOF was successfully synthesized through a one-pot solvothermal method by using 9,10-di(p-carboxyphenyl)anthracene (DPA) as the organic luminescence ligand and Al3+ as the metal node. Compared with DPA, Al-MOF showed high ECL intensity and excellent stability without an additional coreactant in the HEPES buffer. The corresponding ECL mechanism was studied in detail, verifying HEPES was not only the buffer in the system but also the coreactant of Al-MOF. In particular, the system of Al-MOF/HEPES showed a high ECL efficiency of 30.0%, taking the Ru(bpy)32+ system as the standard. In addition, the ECL signal of Al-MOF was effectively quenched by dopamine (DA). The biosensor for HBV DNA detection was constructed through the ECL signal on-off-on mode of DNA specific recognition integrated with the DNA walker signal amplification strategy. The ultrasensitive detection for HBV DNA was achieved with a linear range of 100 aM to 10 pM and a limit of detection (LOD) of 62.1 aM. This work proposed a high-efficiency Al-MOF/HEPES system, providing a new viewpoint for a coreactant-free system in the field of ECL.