Chalcogenide glass is a critical material for thermal imaging systems. Although chalcogenide glass is suitable for molding, the processing characteristics of this brittle material have not yet been thoroughly analyzed. To evaluate the micro-deformation mechanism of chalcogenide glass, a nanoindenter was used to perform indentation, variable-load scratch, and constant-load scratch tests. The experimental data reveal that the discontinuous stepped (pop-in) phenomenon occurs during indentation, indicating that chalcogenide glass undergoes elastic-plastic transformation. Furthermore, the elastic modulus and hardness of chalcogenide glass samples were determined. Upon observing sample morphology after indentation, it is determined that material accumulates at the sample edges. This causes the elastic modulus and hardness calculated using the Oliver-Pharr method to be higher than the experimental values. Therefore a semi-elliptical model should be used to correct the deviations. The depth-length curve for scratch depth was obtained by performing a variable-load scratch experiment. Furthermore, the removal methods of chalcogenide glass during each stage were analyzed. The critical load of brittle-plastic transition is 92.3 mN. Analysis of the scratch test data under a constant load reveals that the critical load of brittle-plastic transition ranges between 50 and 120 mN. This demonstrates the accuracy of the critical load determined using the scratch test under a variable load.