Purpose <p>Increasing evidence has shown that nitrogen (N) deposition profoundly influences soil bacterial diversity and community composition, yet the underlying mechanisms remain incompletely understood. In theory, N deposition can affect soil bacteria by altering forest productivity and subsequent litter inputs as litter provides the primary energy source for soil microbes, but this hypothesis lacks experimental validation. Here, we explored how N deposition and litter inputs interacted to affect soil bacterial communities.</p> Methods <p>We conducted a 10-year factorial experiment with N addition (0 and 10&#xa0;g N m⁻²&#xa0;yr⁻¹) and litter manipulation (addition, ambient, and removal) in a <i>Pinus sylvestris</i> var. <i>mongolica</i> plantation, and measured soil bacterial communities, soil N and phosphorus availability, pH and exchangeable base cations.</p> Results <p>N addition reduced soil bacterial diversity and altered bacterial community composition by increasing soil N availability, and decreasing soil pH and exchangeable base cations. Litter manipulation significantly affected soil bacterial diversity under N addition but not under control treatments. Specifically, litter removal exacerbated the negative impact of N addition on soil bacterial diversity, whereas litter addition mitigated this negative impact. This significant interaction arose because litter removal intensified the N addition-induced increases in soil N availability and acidification, while litter addition alleviated these effects.</p> Conclusions <p>These results underscore the essential role of aboveground litter in maintaining soil bacterial diversity under N deposition, and suggest that forest management practices should strengthen the protection of litterfall to enhance microbial resistance to N enrichment.</p>