The invention provides a measurement method of channel matrix rank as well as a device and a terminal thereof; wherein the method comprises: calculating according to the related information received from a base station by a terminal antenna of a wireless communication system to obtain a channel matrix H to generate a hermitian matrix A; using the hermitian matrix A to construct an equitation set with an eigenvalue of nonnegative real number; calculating the root of the equitation set so as to obtain an eigenvalue of the channel matrix H. The invention can be used for the terminal of the wireless communication system having four transmitting and four receiving antennae and can measure the rank of a four-order matrix, therefore, the base station can determine the number of data flow to be parallelly transmitted according to the current situation of the channel matrix rank so as to increase the number of plural data flow transmitted simultaneously at the same frequency. The method of theinvention is also applicable to the terminal of wireless communication system having two transmitting and two receiving antennae, four transmitting and two receiving antennae and two transmitting andfour receiving antennae.