Abstract: Aiming at the characteristic of OFDM signal and single carrier signal, we firstly applied the fractal theory to the identification for OFDM signal and proposed the identification method for OFDM with fractal dimension box. By mathematically analyzing the fractal dimension box of communication signal, we separately compute the fractal dimension box of OFDM signal and common used single carrier signal and use the fractal dimension box as identification feature to identify the OFDM signal and single carrier signal. The experimental results show that the proposed method has lower computation load and higher identification performance.