An all-dielectric high-power microwave lens array antenna is proposed in this paper. To achieve the required phase shift range of the lens array antenna, two different cell structures are designed and by optimizing the parameters, complementary phase shift ranges are achieved on the basis of ensuring good transmission amplitude. To explore the application in high power microwave systems, a detailed study of the power capacity of the two units is also carried out . Firstly, in the infinite period case, with the change of cell size, the cell power capacity ranges from 1.08-19.37 MW; secondly, the finite period condition is constructed by developing the lens antenna with an aperture of 315 mm×315 mm, and the simulation calculates to obtain that the antenna’s maximum power capacity is 226.553 MW, the power density can reach 2283.23 W/mm², and the antenna can reach a peak gain of 29.37 dBi at the central frequency point of 10 GHz, the aperture efficiency of 62.43%, and the sub-flap level of about -21.54 dBi . The above results show the validity and correctness of the proposed unit, and also indicate that the designed lens array antenna not only has good radiation characteristics, but also has a power capacity of MW magnitude.