Phase shifting device, assembling method thereof and base station antenna

The invention relates to a phase shifter and an assembling method thereof and a base station antenna, the phase shifter comprises at least two phase shifters which are sequentially arranged along the lengthwise direction, the at least two phase shifters can be independently processed and are mutually connected and combined together through a connecting assembly, a cavity with a relatively long length is realized, and the phase shifters are arranged in the cavity. Therefore, the defects that the processing precision is reduced, the production is difficult and the cost is high due to the fact that the length of the cavity is too long are overcome, and the product performance can be correspondingly guaranteed after the processing precision of the conductive cavity of each phase shifter is guaranteed. Besides, the feed butt joint portions and the common ground butt joint portions of the two adjacent phase shifters are located outside the conductive cavities, large enough operation space is provided for mutual con