Coordination polymers (CPs) can be easily functionalized to prepare composite materials to improve their properties. In this study, we report the designed of iron-modified Cd-based coordination polymer composite (Fe@Cd-CP) and photocatalytic activity in removal of antibiotic contaminant and heavy metal. The two-dimensional (2D) layered {[Cd(4-padpe)(1,3-BDC)]⋅H2O}n (Cd-CP) was firstly synthesized by hydrothermal method. Interestingly, the introduction of iron significantly improved photocatalytic performance compared with the pristine Cd-CP. The Fe@Cd-CP composites were applied as bi-functional photocatalysts for simultaneous oxidation of chlortetracycline (CTC) and reduction of Cr(VI) under sunlight irradiation. Based on the detailed experiments, the enhanced photocatalytic performance could be mainly explained by the introduction of iron, resulting in enhanced the harvesting ability of visible light and facilitated the photogenerated electrons and holes separation. Besides, the results clearly displayed that the Fe@Cd-CP composite had good stability and reutilization. The free radical scavenging experiments revealed that ·OH, ·O2-, and h+ jointly participated in the oxidation degradation CTC and the photogenerated electrons took part in the reduction of Cr(VI). Our work proposed a functional strategy for constructing Cd-CP based photocatalyst for environmental remediation.