The present invention provides a reaction cavity and a semiconductor processing device. The reaction cavity comprises a top electrode device and a bottom electrode device, and the bottom electrode device is arranged in the reaction cavity and configured to bear a wafer. The top electrode device comprises a medium cylinder, a coil, a top power source and a top electrode module, and the medium cylinder is arranged at the top of the reaction cavity; the coil is around and arranged at the periphery of the medium cylinder; the top electrode device comprises a top electrode plate, and the top electrode plate is arranged at the top of the medium cylinder; and the top power source is configured to load excitation power to the top electrode plate and the coil at the same time. The reaction cavity can reduce the voltage difference between the output end and the input end of the coil and can weaken the influence generated by a nonuniform electric field so as to improve the plasma density distribution uniformity.