Algae can increase pH and dissolved oxygen via photosynthesis and affect the wastewater treatment performance of high-rate algae ponds (HRAPs). Nine laboratory-scale HRAPs divided into three groups were constructed to treat synthetic wastewater via six-month experiments. Higher algae concentrations in the influent of HRAPs effectively promoted the wastewater treatment performance. Seasonal variation had a significant impact on algal growth. Summer tests exhibited a higher reduction of pollutants than autumn tests. The high-influent algae concentration group in summer (HRAP-A) largely reduced the TN by 52.7±3.0%, TP by 90.3±1.0%, and dissolved chemical oxygen demand (DCOD) by 99.0±1.0%. It outperformed the low influent algae concentration group in summer (HRAP-B) and was significantly higher than the high influent algae concentration group in autumn (HRAP-C). The appropriate operation and design of HRAPs contributed to efficient wastewater treatments.