Sludge treatment is an important part of wastewater treatment and the recovery and utilization of phosphorus from wastewater treatment plant (WWTP) is a challenge for sludge treatment and product disposal. In this paper, eight Chinese typical sludge treatment projects were selected to analyze the species and fractions, and characterization of phosphorus during the sludge treatment process. Furthermore, the nutritional value of phosphorus in the sludge treatment process and the land resource utilization value of phosphorus in the sludge treatment product were discussed. The results showed that the insufficient release of phosphorus to supernatant during anaerobic digestion (AD) of sludge is an important factor restricting phosphorus recovery. Phosphorus in sludge aerobic composting treatment products is mainly in the solid phase, and the concentration effect is beneficial for the phosphorus recovery potential. Phosphorus in sludge treatment products mainly exists in the form of non-apatite inorganic phosphorus, which indicates that improving the bioavailability of phosphorus in sludge treatment products is the key to realizing the nutritional value of the sludge products.