A novel type II BiOCl/CAU-17 2D/2D heterostructure photocatalyst was synthesized by in situ growth of ultrathin BiOCl on the surface of CAU-17 nanorods through a solvothermal process. The 2D/2D heterostructures endow the BiOCl/CAU-17 heterojunction with a large specific surface area and tight interfacial contact, which can provide sufficient channels for carrier migration. The introduction of CAU-17 can enhance the light absorption ability of BiOCl/CAU-17 photocatalysts. Furthermore, the staggered type II heterostructure energy band alignment formed between BiOCl and CAU-17 can promote the separation of photoexcited carriers. The improved performance for carrier migration and light absorption was evaluated by SEM, TEM, BET, EIS, and DRS tests. Transient photocurrent response and photoluminescence tests confirmed the improvement in separating photoexcited carriers. The optimal 70% BiOCl/CAU-17 sample exhibited the highest photocatalytic degradation efficiency of 96.3% for RhB and 85.5% for TC, under 90 min of simulated solar light irradiation. Its apparent first-order rate constant k values are 0.02947 and 0.01955 min⁻¹, respectively, being 48.31 and 19.75 fold higher than those of CAU-17, and 7.61 and 1.84 fold higher than those of BiOCl. The free radical scavenging experiment results showed that h⁺ and ˙O₂⁻ are the prime active species during the photodegradation process. Hence, a possible photocatalytic mechanism of the type II BiOCl/CAU-17 heterojunction was proposed.