The invention discloses a non-orthogonal multi-user access and sending and combined receiving, 
demodulation and coding 
system and method, and belongs to the technical field of communication. The method is characterized in that at a sending end, multiple users have access to the 
system in a non-orthogonal mode, and channel coding, coded 
symbol mapping, 
interleaving and modulation are carried out on a 
signal; at a receiving end, the received 
signal is multiplied by the feature sequence of each user, multi-user detection, 
demodulation, de-
interleaving and decoding are sequentially carried out on the received 
signal, then multi-user detection is carried out on an output result again, and the 
iteration process is achieved. Based on the 
message passing conception, output 
soft information of a decoder is directly sent to undergo multi-user detection so as to achieve decoding and multi-user detection combined iteration 
processing. By means of the method, based on linear 
computation complexity, good 
interference elimination performance can be achieved, influence, caused by 
environmental noise and interference, on signal information is effectively reduced, and good BER performance and a more 
reliable transmission effect are achieved; meanwhile, multi-user 
interference elimination and decoding can be combined to be carried out, and therefore a parallel structure can be easily realized.