Crosstalk noise is an intrinsic characteristic of photonic devices used by optical router which is used in optical networks-on-chip. It also adds a new dimension to the design of the optical router based on the photonic devices. We analyzed crosstalk noise at device level and router level. Based on the detailed analysis, we proposed a general analytical model to study the transmission loss, crosstalk noise, optical signal-to-noise ratio (OSNR), and bit error ratio in the 5 × 5 hitless optical router. For the first time, this paper used the crossing angles of 60° or 120° instead of the conventional 90° crossing angle to design the optical router. It is obtained that by using this method OSNR is improved by about 10 dB.