In this poper.the theory and method of appropriate-measure (AM) dealt with a quantitative means describing the relationship between environment and crops. Two new concepts are put forward .including the process of AM and the AM of the process of the environmental factors'variation for crops. Based on them, a series of models for the AM and the yield of crops have been built up. The theory was used for analyzing the production of the spring wheat in Dingxi, Gansu province and the regular pattern was found ou...