Abstract: Periodic Helmholtz resonators array can be regarded as a typical sonic crystal. By properly tuning the geometries of the resonators and the periodic distance between each two periodic cell, a low-frequency broad forbidden band resulted from both Bragg reflection and the resonance of Helmholtz resonator can be obtained correspondently. However, the periodicity of the structure cannot be perfect as disturbance or defect in the structure may exist. This paper considers the random disorder in a periodic duct-resonator system theoretically and numerically. Two cases are investigated: the disorder in neck length of Helmholtz resonators and the disorder in neck cross-sectional area of Helmholtz resonators. The expectation of the acoustic impedance of Helmholtz resonator is first derived, which further leads to the calculation of ensemble average transmission loss of the overall structure. Moreover, parametric random values of neck length and neck cross-sectional area of the resonator are generated and the corresponding average transmission loss is calculated for with the ensemble average TL. It is shown that the average transmission loss is generally coincident with the ensemble average transmission loss. Furthermore, different disturbing degree is also considered. It turns out that, by comparing with a single Helmholtz resonator, both periodic resonator array and resonator array with disorder have potential application in low frequency broadband noise control as well as in acoustic filtering.