Layers Adjusting External Application can improve the Krenn score of synovitis in rats KOA model, downregulate the expression of serum IL-1β and TNF-α, downregulate the expression of NLRP3, ASC, Caspase-1 protein and mRNA in the synovium, meantime downregulate levels of MMP-1 and MMP-13 in cartilage. The gene discussed is CASP1; the disease is synovitis.