The theoretical analysis is presented for the wavelength-selective reflection-type filter realized by combination of microring resonator array and Mach-Zehnder interferometer. By introducing the series-cascaded two kinds of four-port network, the general formulas are derived with the transfer matrix method, and explicit expressions for the power reflection coefficients of single-ring and three-ring structures are given. The changes of the reflection spectrum shapes are computed for different values of coupling coefficients by the transmission function matrices, and detailed analysis and discussions are given for the reason. For the three-ring structure, the influences of transmission loss on the power reflectivity of resonant peaks are simulated. The simulation results show that: when the ring-bus and ring-ring coupling ratios are selected properly, this device can be used as a reflection-type filter in dense wavelength division multiplexing (DWDM) system and an end mirror for lasers; the degradation of the peak reflectivity value with the transmission loss increase depends on the values of selected coupling ratios.