A sequencing combined beam structure can mix several subbeams with different wavelength fully and the combined beam will have a constant diameter in certain range. A mazy type multipass reflector will multireflect the sequencing combined beam and reproduce the beam structure after every reflection automatically. The multipass laser beam can cover a supposed space. The main principles about the beam structure and the multipass system are presented. The applications in laser epeotroscopy of high-excited atom level and other fields are discussed.