In this paper, thermal postbuckling of a beam-like structure subjected to a uniform thermal loading is studied both theoretically and experimentally. In theory aspect, the equations governing the axial and transverse deformations of beams are derived. The two equations are reduced to a single nonlinear fourth-order integral-differential equation governing the transverse deformations. The analytical method presented here offers a simple yet efficient solution approach to analyze the bistable behavior of microbeam or beam-like structures under thermal loading. Then, microfabricated double-clamped beams are chosen as experimental object due to its precise dimensions and easy loading method. The lab-made HF vapor system was used to release the suspended structures with satisfactory results. After the fabrication and measurement, by comparing the theoretical results with experimental results, an excellent agreement is gotten. It proves not only the validity of the solution obtained here, on the other hand, importantly, it also demonstrates a new field for MEMS as another easy and accurate tool to investigate mechanics problems. With the accurate solutions for posbuckling beams, we apply it into new electrothermal postbuckling actuators, a big deflection promising the possibility of a new kind of actuator.