2025ApJS..280...26S

In this study, we present a comprehensive study of more than 50,000 spectra of 32,257 eclipsing binaries from the LAMOST DR10 survey, including 5200 systems with spectroscopy. We quantified their chromospheric activity through Hα spectral subtraction with iSpec, among 20,000 binaries showing significant excess emission. The chromospheric activity increases toward shorter orbital periods and lower metallicity. By combining tidally locked rotation periods with convective turnover times, we have computed their Rossby numbers and uncovered a geometry-driven shift in the saturation threshold: the detached EA systems saturate at ${\mathrm{logRo}}\,\simeq \,-1.3$ (Ro ≈ 0.05), whereas equivalent width (EW) contact binaries, owing to their common convective envelope (CCE), do not reach saturation until ${\mathrm{logRo}}\,\simeq \,-1.6$ (Ro ≈ 0.025). The CCE enlarges the magnetic-flux reservoir via L₁-spanning field lines and strong shear effects, demanding faster rotation to attain the chromospheric limit. For Ro ≲ 0.02, we observe a mild downturn consistent with supersaturation. The high-precision Transiting Exoplanet Survey Satellite light curves for 4326 eclipsing binaries reveal starspot amplitudes that correlate tightly with the Hα activity, confirming enhanced magnetism in close binaries. We have detected 1752 flare events (1179 from 208 EA, 429 from 44 EB, 144 from EW) on eclipsing binaries. We also determined their parameters and the flare frequency distributions in the different types of eclipsing binaries. In the end, we also give the plan of eclipsing binaries in the LAMOST low and medium-resolution spectra future survey.