Detached eclipsing binaries are remarkable systems to provide accurate fundamental stellar parameters. Fundamental stellar parameters and the metallicity values of stellar systems are needed to deeply understand stellar evolution and formation. In this study, we focus on the detailed spectroscopic and photometric studies of three detached eclipsing binary systems, V372And, V2080Cyg, and CFLyn, to obtain their accurate stellar and atmospheric parameters, and chemical compositions. An analysis of light and radial velocity curves was carried out to derive the orbital and stellar parameters. The disentangled spectra of component stars were obtained for the spectroscopic analysis. Final T-eff, logg, xi, vsiniparameters and the element abundances of component stars were derived by using the spectrum synthesis method. The fundamental stellar parameters were determined with a high certainty for V372And, V2080Cyg (similar to 1-2percent) and with accuracy for CFLyn (similar to 2-6percent). The evolutionary status of the systems was examined and their ages were obtained. It was found that the component stars of V2080Cyg have similar iron abundances, slightly lower than the solar iron abundance. Additionally, we show that the primary component of CFLyn exhibits a non-spherical shape with an 80percent Roche lobe filling factor. It could be estimated that CFLyn will start its first Roche overflow in the next 0.02Gyr.