Porous organic polymers have shown potential applications in gas adsorption/separation, sensing, light-harvesting, catalysis and photovoltaic or electronic devices. In this work, a N-rich porous organic polymer containing s-triazine and Tröger's base has been synthesized through a simple reaction of 2,4,6-tris(4-aminophenyl)-s-triazine (TAPT) and dimethoxymethane. The N₂ adsorption of the polymer at 77 K reveals a type I isotherm of microporous materials, and the polymer exhibits a surface area of 473.1 m² g⁻¹ and CO₂ uptake of 49.8 cm³ g⁻¹ at 1 bar and 273 K. Due to the presence of abundant N binding sites, it shows high isosteric heat for CO₂ up to 33.7 kJ mol⁻¹ and good CO₂ adsorption selectivity over N₂ and CH₄ at 273 K. In addition, the polymer exhibits colorimetric performance for the naked-eye detection of HCl gas, and it has a good stability to recovery. Furthermore, the material can also be used as a heterogeneous basic catalyst of the Knoevenagel condensation reaction between aromatic aldehyde and malononitrile in excellent yields. This general synthetic method may lead to the development of a new class of N-rich porous organic polymers with multifunctions.