Photonic crystal ring resonator can be constructed by putting ring resonators and the waveguides next together. The spectral transmittance and propagation of the optical field entering this system is analyzed numerically using the plane-wave expansion (PWE) method and finite-difference time-domain (FDTD) method. On the basis of this structure,ultracompact multiway beam splitter was designed and the ones with three and four output channels are discussed in details as examples. By simply tuning the radii of coupling dielectric rods in the ring resonators and inducing the redistribution of the optical field,equipartition of energy or free distribution can be achieved. Compared with the results of normal waveguides reported,the most important aspect is that a large separating angle can be obtained in this structure.