Using Janus structures to realize shape transformation is an important method. Here, we present an approach which prepares geometry-switchable Janus micropillars by controlling scanning times of femtosecond laser on a pH-sensitive hydrogel. The applications of the proposed method in encryption, decryption, and display of information are explored. Results show that these micropillars exhibit reversible structural deformation when the pH of the aqueous environment is changed. Because the laser printing technique is highly flexible, the spatial arrangements, pillar heights, and bending directions of micropillars can be readily controlled. Thus, patterns with variable spatial arrangement can be realized.