In this paper, the self-developed calcined water treatment plant sludge (C-WTPS) was used as an active sediment capping material for contaminated sediments. The static simulation experiment was conducted to study the effect of C-WTPS capping intensity on controlling phosphorus release from the sediment. Changes of phosphorus contents with different forms in the C-WTPS and sediment were analyzed, and the effect of thin-layer capping of C-WTPS on the pH, dissolved oxygen (DO) and oxidation-reduction potential (ORP) in overlying water was also discussed. The results showed that during a 40-day experiment, when the total phosphorus (TP) release intensity of the sediment was 6.25-10.87 mg/(m²·d), the TP average reduction rate of C-WTPS with the capping intensity of 0.25, 0.50, 1.00, 1.50 and 2.00 kg/m² were 59.68%, 75.71%, 88.75%, 92.42% and 96.28%, respectively. It means that C-WTPS with a capping intensity over 1.00 kg/m² could restrain over 90% TP from releasing. The phosphorus adsorbed by C-WTPS mainly exist in the form of iron-aluminum bounded phosphorus (NAIP)which were included in the inorganic phosphorus (IP), but the forms of organic phosphorus (OP) and calcium phosphate (AP) were less. C-WTPS promoted the migration of phosphorus which were easily released into the C-WTPS and turn it into the relatively stable phosphorus. It showed that the using capping material C-WTPS could not only control the release of phosphorus from the sediment but also reduce the potential risk of phosphorus release. During the process of C-WTPS capping, the pH of the overlying water began to decline at first, and maintained to be around 7 in the end. The higher intensity of capping was used, the lower pH in the overlying water was discovered. Although, the effect of improving the overlying water by using covering material C-WTPS in the DO and ORP were not obvious.