Aiming at the demand for a low-cost, low-complexity omnidirectional wireless power transfer system under the background of ubiquitous monitoring, an omnidirectional wireless power transfer system using a single power source is proposed from the perspective of coil design. The transmitting coil of this system is designed as a six-side connected cube made of one wire, and the receiving coil is a single rectangular coil. The optimal coil structure is selected through the simulation analysis of magnetic field distribution and mutual inductance characteristics. Experimental results show that transfer power and efficiency at any angle of transmitter coil can meet the requirements of wireless power transfer system. The omnidirectional power transfer law is summarized from the two aspects of transfer distance and angle, which provides basis for the installation range of optimal receiver coil.