Five conservative tracer tests including single nutrient and dual-nutrient injection were conducted to reveal the coupling mechanism of nitrogen and phosphorus uptake in two headwater streams of Ershibu River in the suburb of Hefei, Chaohu Lake Basin, from October 2017 to March 2018. NaCl and NaBr were selected as the conservative tracers; the reactive nutrients were KNO₃ and KH₂PO₄. Based on the TASCC (Tracer Additions for Spiraling Curve Characterization) method, the Michaelis-Menten (M-M) model and the two-substrate M-M response surface model were applied to simulate the kinetics of nutrients uptake. The results showed that the uptake rates of NO₃^-N and PO₄^-P in the dual-nutrient injection test were significantly higher than those obtained in the single nutrient injection test, which implied that mutual promotion between NO₃^-N and PO₄^-P for nutrient uptake in the two headwater streams. The dual-nutrient uptake response surfaces presented the evolutionary trends of uptake rates at different concentrations and ratios of nitrogen and phosphorus. Additionally, it also explained the interaction mechanism of NO₃^-N (or PO₄^-P) uptake rate increasing with the increase of the available PO₄^-P (or NO₃^-N) at their low concentration. The fitting results of NO₃^-N and PO₄^-P maximum uptake rates (U_max-N and U_max-P) obtained by the two kinetic models presented deviations in a certain degree. The parameters of U_max-N and U_max-P were underestimated by the M-M model ranging from 3.91%~16.11% and 3.23%~23.63%, respectively.