Developing novel materials for organic dye photodegradation is of great significance in wastewater treatment. Three Cu I -terpyridyl coordination polymers (CPs, have been solvothermally synthesized and exhibit two-dimensional structures extended by Cu I centers, SCN − , anions, and terpyridyl ligands with different π-conjugated groups. Complexes 1−3 can decompose methylene blue (MB), Rhodamine B (RhB), and methyl orange (MO) with photodegradation rates ranging from 44.4 to 96.8% in 120 min. Owing to the more positive valence band potential and lower band gap regulated by Cu(I) delectrons and pi-electrons of terpyridyl ligands, complex 2 exhibits the highest photocatalytic activity with the order of 2 > 1 > 3 and displays varied photodegradation efficiency for other dyes (Janus green B (JGB) and crystal violet (CV) with rates of 70.4 and 65.7% in 120 min, respectively). The degradation products and mechanism of MB by 2 have been proposed by liquid chromatography− mass spectrometry (LC-MS) and radical quenching experiments. These findings present an effective strategy for designing and synthesizing CPs in photodegradation by increasing the aromatic rings of π-conjugated groups and Cu I center numbers, which may exert important impacts in wastewater treatment.