Sparse decomposition of signal can get sparse representation of signal, and then next disposal can use this sparse representation expediently. But sparse decomposition is very complex (NP problem). Particle swarm optimization is a kind of optimization algorithm using colony aptitude. Its theory is simple to be realized, and the result of searching is good. To reduce complexity of sparse decomposition and space of memory, particle swarm optimization is used in searching the best atom. Particle swarm optimization can increase the efficiency processing signal using sparse decomposition, and then this method can meet (or near) the request of real time. Examinations have proved that this method is feasible.