Abstract: Based on the Cone Index bearing capacity and shearing strength of paddy in Hunan Province, we designed the lug wheel for powered tiller in this province. The principles are: (1) The law of conjugate action from theory of mechanism; (2) The theory of soil mechanics in analysing the soil flow, soil failure and soil reaction forces from experiments on model lug wheel. Through practical ploughing and tilling work of 1 summer season and 2 spring seasons, and also the performance test, the H₄, H₃ lug wheel had been proved to be very well for use in general flooded paddysoil and dry state paddysoil. This lug wheel has passed the identification by Chinese Ministry of Agriculture and the approval of manufacturing and extending for use in Hunan Province.