Abstract: In the free space optical orthogonal frequency division multiplexing (FSO-OFDM) system, nearly 20% of the bandwidth is consumed due to add a cyclic prefix, the data transmission efficiency is reduced. In order to further reduce the bandwidth loss and improve the system performance, a wavelet packet transform was used instead of the Fourier transform in FSO-OFDM, free space optical orthogonal frequency division multiplexing system based on wavelet transform (FSO-WOFDM) was designed. The system didn't need to add a cyclic prefix, and the orthogonality of the wavelet basis functions was used to suppress inter-carrier interference. According to the principle of FSO-WOFDM system, the effects of channel estimation method, turbulence intensity and wavelet based on the bit error rate of FSO-WOFDM system were studied. The system performance of FSO-WOFDM and FSO-OFDM was compared and analyzed. The experiment verifies the feasibility of FSO-WOFDM system and its excellent ability to resist mixed noise.