<p>Frame theory has important applications in phase-retrieval problem, and the dimension function of a frame can serve as a candidate for measuring its phase retrievability. In this paper, we first investigate the relationship between phase retrievability and the dimension function of g-frames incorporating operator theory. We find that the dimension function of a phase-retrievable g-frame closely aligns with that of an ordinary frame. This consistency suggests that the dimension function of a g-frame can likewise act as a metric for measuring its phase retrieval capability. Specifically, we find that the exact PR-redundancy of a g-frame is equivalent to the exactness of its dimension function. The paper then investigates the structure of the dimension function range of g-frames. We find that, even when the number of operators in a g-frame is not less than <i>n</i>, significant differences remain from the case of ordinary frames regarding the structure of the dimension function range of g-Riesz basis and whether the range contains <i>n</i>. Finally, we present a method for examining the dimension function of a g-frame via its induced frame, along with a straightforward approach to construct g-frames whose dimension function range contains <i>n</i>.</p>