Detecting stochastic gravitational wave background from cosmic strings is crucial for unveiling the evolutionary laws of the early Universe and validating nonstandard cosmological models. In light of extensive existing studies on the detection capabilities of third-generation gravitational wave detectors for cosmic string signals, this work provides a systematic evaluation focused specifically on the performance of next-generation ground-based detector networks. By constructing a hybrid signal model that incorporates multisource astrophysical foregrounds, including compact binary coalescences and compact binary hyperbolic encounters, we develop a parameter estimation methodology based on multicomponent signal separation. Numerical simulations using one-year observational data reveal three key findings: (i) The CE4020ET network, comprising the Einstein Telescope (ET-10 km) and the Cosmic Explorer (CE-40 km and CE-20 km), achieves nearly one order of magnitude improvement in constraining the cosmic string tension $G\mu$ compared to individual detectors, reaching a relative uncertainty $\mathrm{\Delta }G\mu /G\mu <0.5$ for $G\mu >3.5\times {10}^{-15}$ under standard cosmological framework; (ii) the network demonstrates enhanced parameter resolution in nonstandard cosmological scenarios, providing a novel approach to probe pre–big bang nucleosynthesis cosmic evolution; (iii) enhanced detector sensitivity amplifies compact binary hyperbolic encounter foreground interference in parameter estimation, while precise modeling of such signals could further refine $G\mu$ constraints by 1–2 orders of magnitude. This research not only quantifies the detection potential of third-generation detector networks for cosmic string models, but also elucidates the intrinsic connection between foreground modeling precision and cosmological parameter estimation accuracy, offering theoretical foundations for optimizing scientific objectives of next-generation gravitational wave observatories.

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• Cosmic strings & domain walls
• Cosmology
• Gravitational wave detection
• Gravitational wave sources