Display omitted ► The instead of Ti substrate with TiO2-NTs greatly improved phenol electrocatalytic degradation. ► Pore diameter and length of TiO2-NTs are crucial to the pollutant degradation efficiency. ► TiO2-NTs architecture affects on the electrode morphology and oxygen evolution potential. ► TiO2-NTs/SnO2-Sb with 85nm pore diameter and 5μm length TiO2-NTs performed the best. There are growing interests in the TiO2 nanotubes (TiO2-NTs) based Sb-doped SnO2 anode (TiO2-NTs/SnO2-Sb) for organic pollutants degradation due to its high oxygen evolution potential and enhanced degradation performance. However, whether and how the TiO2-NTs substrate architecture of the electrodes affects the electrocatalytic capability for organic pollutant degradation has not been reported yet. This work addressed this issue, investigating the effect of the pore diameter and length of TiO2-NTs on the electrocatalytic capability of TiO2-NTs/SnO2-Sb electrode, which was fabricated by Sb-doped SnO2 coating electrodeposition on different TiO2-NTs architecture substrates by successfully adjusting the Ti substrate anodization time and voltage. The characterizations of morphology, crystal structures and composition as well as the electrochemical characteristics were comparably studied. It confirmed the modification of TiO2-NTs substrate greatly improved the electrocatalytic degradation of organic pollutant, using phenol as the target contaminant. The pore diameter and length of TiO2-NTs substrates of the TiO2-NTs/SnO2-Sb electrode were verified to be crucial to the pollutant degradation efficiency, and the one with TiO2-NTs of 85nm pore diameter and 5μm length performed the best.