Two-dimensional (2D) materials as platform may exhibit abnormal physical properties associated with guest dynamics, such as contracting/expanding, mutual sliding, close/open due to inherent flexibility of interlayers. However, it is still underexplored research. Herein, we report a bilayer porphyrinic 2D metal-organic framework (MOF) showing abnormal guest-responsive thermal expansion. The crystal shows nonlinear and large thermal expansion over a critical heating point, as movements of guest molecules in accessible to direction. More significantly, it instantly responds to the rearrangement of guest molecules, leading to anisotropic expansion in interlayer of the framework without destroying crystallinity, demonstrating single-crystal X-ray crystallography and electron density mapping. These results indicate that flexible 2D material could be suitable platform for the performance of external physical stimuli, including liberal guest molecules.