We investigated photonic crystals based dual nano-ring channel drop filters which are nanomechanically tunable. The backward channel drop mechanism is explained by a proposed model. Resonant peak observed on the free stand device is located 1553.6 nm with quality factor better than 3800 at backward drop port. When this dual nano-ring is integrated at the junction between silicon cantilever and substrate, the deformation of silicon cantilever can shift the filter resonant wavelength. The 1nm wavelength shift is derived by minimum tuning force of 370nN.