The influence of filtering characteristics of lossy series coupled two-microring resonators was studied.When the coupling coefficients between the two rings were fixed,under the perfect coupling condition,the influence of the loss on transmittance of the main resonance peak,bandwidth,shape factor and peak transmittance of the spurious modes were analyzed.The effects of the loss on these filtering characteristics were demonstrated.Analysis shows that the transmittance of the spurious modes and the main resonance peak decrease with the optical loss,the coupling coefficients between the two rings and the straight waveguides become smaller,and the bandwidth and the shape factor of the main resonance peak change little.The coupling coefficients between the rings and the straight waveguides should not be too big or small.