Abstract: 【Objective】 This study aimed to investigate the effects of three types of dispersants(acid-based, aminebased, and bifunctional) on the surface modification of silver powder, clarify the intrinsic correlation between the physical and surface properties of modified silver powder and the fineness of silver paste prepared therefrom, and provide a reliable theoretical and technical basis for optimizing the silver powder modification process and improving the preparation efficiency of high-performance silver paste in powder metallurgy.【Method】 Three types of dispersants, including acid-based(lauric acid), amine-based, and bifunctional ones(LD-109 and BYK-410), were adopted as modifiers for silver powder surface treatment. SEM observation and agglomeration factor quantitative analysis were combined to evaluate the dispersibility of modified silver powder. Tap density and bulk density tests were carried out to compare the compactness of silver powder modified by different dispersants. XRD detection was used to analyze the crystal structure and crystallinity of silver powder before and after modification. Contact angle tests were performed to determine the hydrophilic-lipophilic balance of modified silver powder, and the fineness of silver paste prepared from modified silver powder was tested after three-roll grinding to explore the correlation between silver powder properties and paste fineness.【Result】 Different types of dispersants cause significant differences in the physical properties of silver powder due to their different adsorption mechanisms on the silver powder surface. Among them, the silver powder modified by lauric acid exhibits the best dispersibility, with the lowest agglomeration degree and the most uniform particle distribution observed via SEM. Bifunctional dispersants(LD-109, BYK-410) result in significantly higher tap density and bulk density than single-functional acid-based or amine-based dispersants. XRD test results confirm that dispersant modification only acts on the silver powder surface and does not alter its intrinsic face-centered cubic crystal structure and high crystallinity. Notably, silver paste fineness has no direct correlation with silver powder dispersibility or density but is highly correlated with its contact angle characteristics. When silver powder is in an incompletely wetted state with water, terpineol, or diethylene glycol butyl ether, the prepared silver paste can easily meet the ≤5 μm fineness requirement after three-roll grinding, and the number of grinding passes required is significantly reduced compared with completely wetted silver powder.【Conclusion】 Bifunctional dispersants show obvious advantages over single-functional ones in improving the compactness of silver powder, while lauric acid is optimal for enhancing silver powder dispersibility. Dispersant-based surface modification is a non-destructive treatment method that preserves the crystal structure and inherent physical and chemical properties of silver powder. The contact angle of silver powder is the key factor determining silver paste fineness, and regulating the wettability of silver powder with water and organic solvents can significantly improve the grinding efficiency of silver paste. This study provides practical guidance for the rational selection of dispersants in silver powder modification and the optimization of silver paste preparation processes, which is of positive significance for promoting technological progress in related powder metallurgy fields.