Abstract: With the progression of industrialization, an increasing number of emerging contaminants (ECs) have entered natural water bodies. Among these, per- and poly-fluoroalkyl substances (PFASs) are a particular class of synthetic compounds characterized by their exceptional stability, bioaccumulation potential, and toxicity, posing significant threats to human and ecological health. This study introduced calcium chloride (CaCl₂) into the aqueous phase to facilitate the chelation between Ca²⁺ and acyl chloride monomers, thereby internally regulating the interfacial polymerization (IP) reaction. As a result, a CaCl₂-modified nanofiltration membrane (CaCl₂-TFC) was successfully prepared, featuring a thinner, rougher, more hydrophilic surface with enhanced negative charge and a lower molecular weight cut-off. The impact of CaCl₂ concentration on the separation performance of the nanofiltration membrane was investigated. The results indicate that the modified membrane achieves a pure water flux of 101.86 L·m^-2·h^-1, nearly 3.28 times that of unmodified TFC membrane, with a Na₂SO₄ rejection rate of 95.61%, overcoming the trade-off effect of TFC membranes. This alleviates the trade-off effect between water permeability and solute rejection to some extent. Furthermore, the membrane exhibites rejection rates of 95.78% and 90.92% for PFHxA and PFHxS, respectively. This research presents a simple, environmentally friendly, and low-cost method for the fabrication of TFC NF membranes, applying it to the treatment of PFASs and providing a technical reference for ensuring drinking water safety.