A new method based on bi-spectrum for generating random driving signal in time domain is presented for multi shakers in random vibration test. Firstly, the equivalent relationship of amplitudes and phases between auto-spectrum and bi-spectrum are established, Secondly, MIMO linear system are supposed, relations between driving bi-spectrum and response bi-spectrum are set up, inverse operation are used for calculating the driving bi-spectrum, Finally, the equivalent relationship are obtained, random driving signal in time domain according with reference requests are got. A numerical example is done, the result show existence of the equivalents. At the same time, random vibration experiment about cantilever beam is made to prove the effective aspects of the method.