A fixed-coefficient variable prime length recursive discrete Fourier transform system includes a pre-processing device, a real-part computation device, an imaginary-part computation device and a post-processing device. The pre-processing device receives N digital input signals and performs order permutation operation to generate first and second temporal signals, wherein N is a prime number. The real-part computation device receives the real part of the first and second temporal signals and performs discrete cosine/sine transform to generate third and fourth temporal signals. The imaginary-part computation device receives the imaginary part of the first and second temporal signals and performs discrete cosine/sine transform to generate fifth and sixth temporal signals. The post-processing device receives the third, fourth, fifth and sixth temporal signals to perform order permutation and addition operations for generating N digital output signals, wherein the N digital output signals are the discrete Fourier transform of the N digital signals.