Abstract：Extracellular polymeric substances （EPS） play an important role in sludge settlement. This research was based on the one-stage combined partial nitritation and anammox process. Given the sludge bulking problem， the sludge bulking was controlled by stopping dosing sodium acetate， adjusting SRT and aeration stop ratio， and the change characteristics of extracellular polymers in the whole process were investigated. The results showed that in stage I-II （0~77 d）， although SVI rose to 215.86 mL?g-1， the TN removal rate remained stable at 60.88%； in stage III （78~109 d）， SVI remained at 210.16 mL?g- 1，TN removal rate dropped to 32.19%， stage IV （110~140 d）， SVI dropped to 107.53 mL?g-1， TN removal rate also recovered to 54.55%， AOB， NOB and ANAMMOX activities correspondingly recovered to 0.42， 0.06， 0.20 g?g-1?d-1. After sludge bulking was controlled， the main components that affect the solubility of EPS （Solubility EPS， S-EPS） and solubility protein （Solubility PN， S-PN） decreased from 243.15， 213.25 mg?g-1 to 110.97， 49.52 mg?g-1. Three-dimensional fluorescence spectroscopy analysis shows that the PN content increased and the PS content decreased while adding sodium acetate. PICRUSt2's analysis of PN and PS metabolism also shows that after the sodium acetate was stopped， the abundance of amino acid metabolism genes decreased， the hydrophobicity increased and more PS was converted into endogenous organic matter for microbial utilization.