Abstract: Discussion on vector properties of angular physical quantity，through graphic

comparison，or through formula calculation，many papers draw the conclusion that infinitesimal

rotation is vector and finite rotation is not vector.Neither point out the physical

fundamental reason. According to the invariance of physical quantity and the covariance of

transformation，it is proved that the rotation vector is not true vector，that of the essential

reason is the levorotation and dextrorotation of the coordinate system.

Key words: vector, tensor, inversion, parity