Abstract: The rate of coal desulphurization can be promoted by microwave irradiation much more, which have be recognized and validated from recent experiment results. However, there still exist many unanswered questions, which creates significant limit on its development. To investigate the best frequency for such a microwave reaction, a frequency reconfigurable microwave reaction experiment apparatus is proposed and designed in this paper, including a wideband microwave source, a wideband microwave transmission system, and a frequency reconfigurable reactor. This apparatus offers a 67% tunable bandwidth to cover the operation frequency range of 500 ～ 1 000 MHz. Compared with other reaction apparatus with the same function, our design is simple and low cost. Furthermore, it can be employed in other microwave chemical experiments.