As a kind of efficient photocatalyst, coordination polymers (CPs) have gained much attention in recent years. However, their safety issue and time-consuming synthesis impede their practical application. Here in this paper we first demonstrate the facile synthesis and photocatalytic degradation performance of 1D α-ferrous oxalate dihydrate (α-FOD), which is one of the simplest CPs. A unique two-pathway photocatalytic mechanism which combines traditional photocatalytic and photo-initiated Fenton oxidations has been proposed. The excellent photocatalytic performance and cost-effective fabrication make α-FOD a new promising candidate for the photocatalytic degradation of organic pollutants in practical applications.