Abstract: Through the analysis of the monitoring data of the Yellow River, it is found that the turbidity has a great influence on the monitoring data of the total phosphorus in the automatic water quality station. According to the coefficient of variation analysis, there was a correlation between turbidity and total phosphorus, which affected the total phosphorus monitoring value. It was confirmed that there was a positive correlation between turbidity and total phosphorus value when the pretreatment method was larger than 400NTU for 2min and when the pretreatment method was smaller than 400NTU for 1min. In order to ensure the authenticity of the monitoring data from the automatic water quality station in the Yellow River section, it was suggested that during the dust season from March to September and the rainy season, the pretreatment method should be modified to centrifugation for 2min.