The form distribution of phosphorus (P) in ten surface sediments from the upper reaches of the Yellow River, China, was studied using the sequential chemical extraction procedure-the standards, measurements and testing harmonized procedure. The equilibrium and thermodynamics of P adsorption onto sediments were evaluated. Five fractions of sedimentary P, including metal oxide bound P (NaOH-P), calcium bound P (HCl-P), inorganic P (IP), organic P (OP) and concentrated HCl P (total P, TP), were separately quantified. The results indicated that the contents of different P fractions in sediments varied greatly. The mean of TP content was 657.57 mg/kg, and averages of NaOH-P, OP, HCl-P and IP contents represented 4.03%, 8.85%, 82.10% and 88.69% of TP, respectively. HCl-P was the major component of IP and TP. the amount of potential bioavailable P was approximately estimated 12.88% of TP. The equilibrium data of P adsorption on different sediments fitted perfectly for Langmuir and Freundlich models. the adsorption amounts of P decreased with increasing temperature. The negative values of thermodynamic parameters ΔG and ΔH indicated the spontaneous and exothermic nature of the sorption.