The fifth generation (5G) mobile communication technology is the research hotspot in the field of mobile communication at home and abroad, whose biggest characteristic is high bandwidth and low delay. However, Orthogonal Frequency Division Multiplexing (OFDM) technology has high frequency utilization rate and anti-multipath interference, as a key candidate technique for 5G, which can effectively resist frequency selection fading and so on, and thus has been widely concerned, researched and popularized. In this paper, the basic principle, modulation and demodulation block diagram of OFDM are described, and the performance of OFDM systems’ Bit Error Rate (BER) under Quadrature Phase Shift Keying (QPSK) and 16-QAM modulation is simulated analysis. The simulation results indicate that the performance of QPSK modulation advantages over that of 16-Quadrature Amplitude Modulation (16-QAM), and OFDM technology can guarantee the reliable transmission of multiple antenna signals under the condition of constant bandwidth.