In the design and development of the current conveyor line system, problems such as cumbersome work, poor flexibility for modification, and complicated on-site installation and debugging are common in links including the structure design and layout program planning, on-site installation and debugging of the control system, and real-time conveyor path planning of large-scale systems. Considering this, this study designs and develops a Unity3D-based simulation system for modular conveyor line design. On the basis of the three-dimensional (3D) model of the modular conveyor Unity3D, the modular and rapid assembly construction of the design scheme is realized through Winform human-computer interaction. The soft PLC technology and distributed controller architecture are used to achieve off-line programming and quick on-site installation of the conveyor line control system. The optimal path of material transportation is planned by the genetic algorithm, and the simulation operation of the conveyor line system is finally completed. The result comprehensively verifies the effectiveness and correctness of the system design scheme, control programming, and path planning and lays a foundation for the subsequent rapid design and on-site installation of conveyor lines.