Analysis of blast mechanism has revealed the qualitative relationship of rock behaviour with blast effect. On this basis, a host of data gained in the study and practice of blasting operations in mines were analyzed using grey theory, and the quantitative relationship of rock behaviour with blast effect was examined. Thus it came to the conclusion that parameters concerning rock behaviour such as transversal wave speed, longitudinal wave spe'ed and rock strength are in the order of degrading importance to influnce blast effect.