Abstract: The influences of flowing agricultural particle material arching in hole are discussed in this paper. The arching mechanical models are developed on the basis of micromechanical priciple. The critical arching condition of flowing particle material in hole is analysed as well. The relationships of the particle size, critical hole diameter and arch highness are derived. The patterns of relationship between the size and moisture of particle and critical hole diameter are estiblished based on the experiments and thus information is provided for the design of agricultural material and food mechinery, as well as for the furture research.