In view of the problems lying ahead of “low slow small” target detection, a grid based concept is proposed, a definition of grid based perception system is given, and a grid based perception system is designed, including sensor subsystem, communication subsystem, management and control center, and comprehensive support subsystem. The paper analyzes the key technologies of grid based perception systems, including low-cost sensor design, “low slow small” target detection, data fusion processing, and other technologies. The deployment principles of grid based perception systems are researched and a deployment principle model is established. And the above-mentioned reasons have, to a certain extent, practical guidance significance for solving the problem of “low slow small” target detection.