The invention provides an antenna mode switching method of a multiaerial system, which is applied to the multiaerial system supporting space multiplexing and beam forming antenna mode. The antenna mode switching method comprises the following steps: A: a channel matrix H is estimated at a receiving terminal, B: if the specific value ki of the maximum singular value Lambda max (H) of the channel matrix H and other singular values Lambda i (H) except the maximum singular value is equal to the minimum value min (ki) of Lambda max (H) / Lambda i (H), which is less than or equal to the lower limit threshold value kSM of the set standard channel condition number, so the antenna mode is switched to the space multiplexing mode; C: if the min (ki) is more than or equal to the upper limit threshold value kBF of the set standard channel condition number, the antenna mode is switched to the beam forming mode, wherein the ki is unequal to 1, i is equal to 1, 2, and the like, N-1, and N is the minimum value of sending the antenna number and receiving the antenna number. The invention discriminates the antenna switching mode through adopting two-stage judgement mode, thereby quickening the choosing and switching speed of the antenna mode, and improving the choosing and the switching accuracy of the antenna mode.