Abstract: This paper basically studies the mechanics properties of the rockmass discontinuity for the especial stress state of the rockmass in the current engineering, analyses the results of the shearing test of rockmass discontinuity under loading and unloading, some laws of the strength property of the rockmass discontinuity are made, and compares them, Then makes some conclusions about the strength property of rockmass discontinuity, and presents a formula about shearing strength of rockmass discontinuity to make up the deficiency of the classical theory.