In this paper， a pseudo-ternary phase diagram and star point design-response surface optimization were used to prepare the coix seed oil self-nanoemulsifying delivery system（CSO-SNEDS）， and the characterization and in vitro release studies of CSO-SNEDS were investigated. The results show that the optimal component of the formula is Tween60 / Span20 / glycerol / coix seed oil. Among them， the coix seed oil mass fraction was 16.11%， and the ratio of the composite surfactant（Tween60 / Span20=9∶1） to cosurfactant（glycerol） is 3.54. The CSO-SNEDS is a clear， transparent liquid that appears yellow. After dilution， it can form a uniform and stable nanoemulsion. The average particle size， polydispersity index， and ζ-potential are 47.52 nm， 0.188， -15.7 mV， respectively. The in vitro release kinetics of CSO-SNEDS in artificial gastric fluid and artificial intestinal fluid complies with the Ritger-Peppas equation with fitting coefficients of 0.731 and 0.912， respectively. Both release mechanisms are consistent with Fickian diffusion.