In this paper, a set of general constraint conditions of 3 port power divider is newly established for arbitrary power ratio and arbitrary phase difference, where, the relationship between power ratio and phase difference can be newly summarized as a very simple equation. To verify this theory, a novel power divider with three standard 50 Ω ports is presented, and it consists of an isolation resistor and seven transmission lines. From the design charts and several design examples, the proposed power divider could not only provide arbitrary power ratio and arbitrary phase difference, but also independently control their fractional bandwidths (FBW or FBW) under various combinations of power ratio and phase difference. In final, two prototypes are fabricated, and the measured results matched very well with simulated results.