Background: Perineural invasion (PNI) is a key biological feature underpinning the high malignancy and poor prognosis of pancreatic ductal adenocarcinoma (PDAC). Lysine lactylation (Kla), a metabolite-stress-induced post-translational modification, plays crucial regulatory roles in diverse biological processes. The RNA methyltransferase NSUN2 is essential for cancer invasion and metastasis. However, the mechanisms by which NSUN2 contributes to lactylation-driven PNI in PDAC remain to be elucidated. Methods: We assessed tumor lactate / pan-lactylation, NSUN2 lactylation, and PNI in human PDAC cohorts with survival follow-up. Functional studies used PDAC cell lines for migration/invasion assays, dorsal-root-ganglion (DRG) co-culture, and neurite-outgrowth assays under lactate or enzymatic perturbations. Mechanistic interrogation combined NSUN2 knockout, CRISPR knock-in mutants at K692 (K692R/E), co-immunoprecipitation, RIP-seq, MeRIP-qPCR, and actinomycin-D chase to test mRNA binding, m5C modification, and stability of CDCP1/STC1. In vivo validation employed a sciatic nerve invasion model and a KPC genetically engineered mouse model to assess tumor-nerve infiltration and disease progression. Results: Lactylated NSUN2 is markedly upregulated in mice and human PDAC with more severe PNI, and is significantly associated with poorer prognosis. Functionally, inhibiting lactylation or blocking NSUN2 markedly attenuated tumor-nerve interactions and neural invasion. Mechanistically, lactate accumulation leads to the lactylation of NSUN2 at lysine 692 (K692), subsequently inhibiting its ubiquitination and degradation. lactylation of NSUN2 mediated m5C modification on CDCP1 and STC1 mRNA, enhanced their mRNA stability. Conclusions: This study identifies lactate-driven NSUN2 K692 lactylation as a key driver of perineural invasion in PDAC. We define a lactate-NSUN2-m5C-CDCP1/STC1 axis that links metabolic stress-induced lysine lactylation to mRNA methylation-dependent stabilization of pro-invasive transcripts, highlighting actionable therapeutic targets to restrain neural invasion and improve patient outcomes.