In the traditional parallel micro-ring structure, we can achieve the slow light effect tuning by adjusting the coherence distance, but cannot achieve dynamic tuning. Improved micro-ring array, embedding the heater in the cladding, uses thermo-optical tunability to adjust the adjacent ring between the phase shifter, in order to achieve continuous adjustment of any channel slow light effect. We use the transfer matrix method to establish the function model of dense wavelength division multiplexing (DWDM) and simulate the slow light effect of 1×4 DWDM by Matlab. The simulation results show that the DWDM with tunable optical delay channel is obtained by changing the additional phase shift between the corresponding microcircuits, the full width at half maximum (FWHM) of spectral intensity for out channel is about 0.05 nm, and the channel spacing is 100 GHz. The method can switch and dynamically adjust optical delay channel, and enhance the flexibility of the optical device.