Abstract: 208 groundwater samples were collected within Heze, the key representative region in the Yellow River alluvial plain over the southwest of Shandong Province, to investigate the compound concentration, geographical distribution and physical causes of groundwater fluoride and iodide. Results of the analyses show that the fluoride concentrations for all the deep groundwater samples exceed the threshold limit of class Ⅲ (1.0 mg·L^-1) of "Standard for Groundwater Quality" (GB/T 14848-2017), and 60.3% of the shallow groundwater samples exceed the threshold limit of fluoride concentration. Moreover, 61.8% and 56.3% of the deep and shallow groundwater samples, respectively, exceed the recommended standard value of iodide concentration (≤ 0.15 mg·L^-1) derived from World Health Organization. In addition, well depth plays a significant role on the fluoride and iodide concentrations. In shallow well, fluoride concentration increased with the increase of water depth, while the severe over-standard rate of iodide concentration declined with the increase of water depth, and the water samples that were seriously exceeding the standard value mainly concentrated within 30 m of water depth. In deep well, the water samples with the fluoride and iodide concentrations seriously exceeding the standard value were principally concentrated below 400 m of water depth.