STLINAC-6/9MeV/3000 is a modular high energy electron linac with a variety of optional equipment, which can meet the different requirements of NDT and security inspection applications. It adopted S-band standing wave electron linear acceleration technology, magnetron as microwave power source and standing wave electron linear accelerating tube as core component to producing high-energy X-rays. The STLINAC system is mainly composed of LINAC head, control console, modulator, temperature control unit, cables and water pipes.