Abstract: Present a design of configurable high-precision FFT/IFFT processor. The whole design uses mixed radix serial architecture, reducing the system complexity and saving hardware resource. Present a novel block floating point algorithm which solves the overflow in long point FFT effectively and improves precision. The point can be configed to 64、128、256、512、1024 by controlling counter for generating address, and the real and imaginary parts of data are 16 bits, the design not only can implement FFT, but also can implement IFFT. The proposed processor is designed in a SMIC 0.13μm CMOS process, the area is 1.55mm².The highest clock frequency is 210MHz. The test result shows high-precision of the design.