Due to the advantages of fast response, multiple factors metering and easy implementation, the measurement method of light-screen array has been widely used in the measurement of external ballistic flight parameters of barrel rapid-fire weapons. Compared with the separated light-screen array, the integrated light-screen array measurement model has the advantages of simplified parameters, simple model and easy to use. In this paper, a seven-light curtain array measurement model is proposed, key light curtain structural parameters in the model are obtained, the model is established and simulation analysis is carried out. And a set of structural parameter optimization method is obtained by discussing the influence of each parameter on the measurement deviation of the flight speed and position of the projectile. Based on the optimized structural parameters, the error distribution of the projectile’s flight velocity and position coordinates is obtained in the 1 m×1 m rectangular target area. The model method presented in this paper can be used as the design basis of the optical curtain array measurement device, and can also provide guidance for improving the accuracy of the measurement of the projectile motion parameters of the linear propulsion mechanism.