Abstract: In view of the serious multi-access interference in traditional transform domain communication systems(TDCS), which can suppress the performance of users and bit error rate, a partition multi-access interference reduction method is proposed, which is suitable for large-scale transform domain multi-access communication. Firstly, an evenly division method is proposed divide users into inner partition users and outer partition users which respectively contributes to performance improvement of spectral efficiency and bit error rate, and the formula of bit error rate is derived. Then, the partition vector calculation method is proposed which introduce CAN algorithm to improve the auto-correlation of the partition vector and further reduce bit error rate. Last, the overall performance of the method is analyzed from the aspects of spectral efficiency and bit error rate under Gaussian channel, and the optimal length of the partition vector is given. Simulation results show that as the number of users increases, this method can ensure the bit error rate within a certain range and the spectrum efficiency stable. Therefore, this method can effectively increase the number of users of TDCS.