In this paper, a compact four-way radial-cavity-based power divider/combiner have been designed, simulated and discussed. A substrate embedded by the inner conductor with an isolating circuit linking with four star-type resistors on it is employed for enhancing isolation of every input ports. Simulated results show a good performance within the operating frequency range from 8GHz to 9GHz, where the return loss of each ports and isolations between pairwise input ports are all greater than 20dB. The structure also shows an appreciable ability on combining efficiency and power capacity due to the cavity based.