Detailed measurements of radiation spectra of individual emitters in CW laser diode bars (LDBs) were done. For the first time, the anomalies in the measured spectral distributions over the emitting apertures were observed, which can not be explained through consideration of measured and modeled relatively smooth temperature distributions over the LDBs. Explanation of these spectral features in the measured spectral distributions along LDBs has been achieved with numerical modeling of not only the temperature profiles but also thermo-elastic stress in LDBs that can strongly affect the radiation characteristics of emitters. Three main mechanisms of the thermo-elastic stresses occurrence in operating LDBs have been considered: “initial” stresses in an unbounded bar, stresses as a result of the assembling process, and stresses as results of working regime of LDB. Understanding of demonstrated experimentally and theoretically effect of thermo-elastic stresses on spectral behavior of emitters in LDBs will promote development of new generation of high-power laser systems, in particular, with beam summation via spectral combining method.