By adopting four parallel-coupling one microring resonator as basic routing elements, a kind of four-port optical router is proposed, which can passively route three channel wavelengths. The structural parameters of the routing element were optimized for single-mode transmission, low optical loss and phase-match between microring waveguide and channel waveguide. The device architecture as well as design scheme of the router was presented, and routing characteristic including spectrum characteristic, insertion loss and crosstalk were calculated. Under the selected three channel wavelengths of 1 550, 1 551.6 and 1 553.2 nm, the insertion losses along all routing paths are within 0.02~0.6 dB, and the crosstalk ranges from －23.41 to －37.71 dB. Compared with the previously reported four-port optical router using cross-coupling two microring resonator and the same waveguide parameters, the proposed router reveals slightly higher crosstalk and inferior spectral selectivity, but it does show smaller insertion loss (decreasing from 1.62 dB to 0.02 dB) and uses less rings (decreasing from 8 to 4).