Abstract: Reflective enhancement has been proved to be an efficient way to raise the transfer efficiency of 266nm laser generation by the fourth harmonic generation (FHG). However, the reported enhancement cavities have some disadvantages, such as, the light beams reflected by different times are not overlapped well and the beam quality of violet light is poor. In order to obtain better beam quality, a new reflective cavity was described to realize the well overlap of the beams reflected by different times. The beam profile and transfer efficiency were calculated. The results show that a good beam quality of FHG violet light can be achieved and the efficiency of FHG can be further improved.