Photo-chromic liquid crystal polymer networks (LCNs) is a smart material for the great light-activated variation or bend to transfer luminous energy into mechanical energy.We study the light induced behavior by modeling planar and homeotropic nematic network polymer plates.We effectively illustrate some reported experimental outcomes and theoretically predict some possible bending patterns.This paper constructs an understanding between the bending behaviors and interactions among the alignments,aspect ratios and boundary conditions, etc.Our work gives an instruction on optimizing light induced bending in the process of Micro-Opto-Mechanical Systems (MOMS) design.