The filtering properties of all-fiber acousto-optic tunable filter (AOTF) based on cladding etched sing-mode fiber (SMF) are investigated experimentally. Influenced by the acousto-optic effcect, the acousto-optic coupling efficiency from LP01 core mode to LP11 cladding mode is enhanced by reducing the cladding diameter. At a fixed cladding diameter, the resonant wavelength of the AOTF shifts to the shorter wavelength side as the acoustic frequency increases. Moreover, the change of resonant wavelength with the acoustic frequency is numerically calculated and the simulation curves are in good agreement with the experimental results. The axial strain characteristics of all-fiber AOTF based on cladding etched SMF are analyzed experimentally. The results show that the resonant wavelength appears red shift as the increasing of axial strain, so it′s easy to achieve the tunable filter using the axial strain dependence. The tuning bandwidth is inverse to the acousto frequency and the cladding diameter. When the cladding diameter is kept at 35 μm and the acousto frequency is fixed at 1 MHz, an AOTF with tuning bandwidth greater than 150 nm is demonstrated.