Abstract: In light of the persistent surveillance requirements for aerial targets in the context of low-Earth-orbit （LEO） mega-constellation networking， a novel technical approach can be developed by the integration of LEO satellite networking characteristics and forward-scatter detection technology to enhance aerial situational awareness. However， existing satellite-ground detection analysis methods do not involve systematic investigation of forward-scattering detection networks in scenarios of dynamic mega-LEO constellation. First， to clarify the parameter applicability range of the forward-scatter detection system in LEO mega-constellations， we established a forward-scatter bistatic power model and a maximum detection range model. These models are based on parametric evaluations of the detection performance of single-transmitter-single-receiver basic units constituting the system for targets of different sizes. Second， within the applicable parameter range， the detection coverage of the joint network comprising basic units is modeled as a collection of “shadow cone units”. Based on the geometric constraints and performance boundaries inherent in forward-scatter detection， two key metrics are proposed for evaluating system performance： effective coverage ratio and detectable elevation threshold. Finally， simulations of dynamic constellation scenarios across four LEO mega-constellation development stages reveal the geometric coverage capability and detection performance boundaries of the forward-scatter network in a “multiple-transmitters-single-receiver” configuration. This study demonstrates that when the typical distance between the satellite and the aerial target is 600 km， the coherent integration time of the received signal is 1 ms， and the effective isotropic radiated power （EIRP） of the satellite is ≥45 dBW， reliable detection of 100 m²-level targets are achieved by ground receiving stations at a range of 10000 m. Under the parameters of Starlink-like constellation， if the wavelength-to-target contour size ratio is ≥0.2， with 9998 satellites and a system observation cutoff elevation ≥15°， the system achieves an average effective geometric coverage of 78.36% of the conical airspace. Furthermore， in airspace with detection elevations >20.2°， the system can cover targets with a cruise altitude of 1 km and a square contour size of 5 m. In this study， the detection performance boundaries of LEO mega-constellation forward-scatter detection systems are quantified systematically for the first time and the system detection capabilities at different mega-constellation development stages are revealed， providing theoretical support and parameter optimization pathways for the design of next-generation space-air collaborative detection systems.