<p>A quantitative study of inclusions in an industrial superalloy ingot produced by vacuum arc remelting (VAR) was conducted, and the characteristics as well as the formation mechanism of non-metallic inclusion clusters were discussed. Results showed that inclusions within the VAR ingot primarily consisted of individual nitrides and composite inclusions such as oxide–nitrides. The quantity density of individual inclusions increases radially from the center to the edge of the ingot, while decreasing axially from the top to the bottom, with the average size gradually decreasing in both radial and axial directions. Clustered inclusions were identified in the subsurface regions (2–10&#xa0;mm in&#xa0;depth) and sidewall surfaces of the ingot. The formation mechanism and distribution characteristics of clustered inclusions during the VAR process were studied by combining in-situ high-temperature laser confocal microscopy observation and numerical analysis. In-situ observations confirm that larger inclusions lead to reduced critical aggregation distance, while smaller spacing enhances attraction and promotes cluster formation. The cavity bridge force between inclusions is significantly greater than the capillary force and van der Waals force, serving as the primary force responsible for the aggregation of inclusions. Numerical analysis reveals that inclusions within the VAR melt pool exhibit typical flow-following behavior and size effects, with their trajectory leading to preferential accumulation patterns along both the sidewall and subsurface regions, thereby facilitating cluster formation through particle agglomeration.</p>