Abstract: Severe acute pancreatitis (SAP) is characterized by both local and systemic inflammatory responses. This study was designed to develop a site-specific delivery strategy for SAP therapy using celastrol (CLT). First, murine RAW264.7 cells were used as a model of macrophage cell line, cell membranes were obtained by emptying intracellular contents via hypotonic lysing, mechanical membrane disruption, and differential centrifugation. Poly(ethylene glycol) methyl ether-block-poly(lactic-co-glycolic acid) (PEG-PLGA) nanoparticles (NPs) were then prepared by sonication. With the collected membrane materials, macrophage membrane coated PEG-PLGA NPs (RNPs) were then prepared by extrusion through a 400 nm polycarbonate membrane. Biodistribution study in rats with SAP showed RNPs selectively accumulated in the inflamed pancreatic tissues. Compared with CLT loaded NPs, CLT loaded RNPs were proven to effectively attenuate local pancreatic inflammation and systemic inflammation in rats with SAP.