many methods of primer design have been proposed to provide feasible primer sets for polymerase chain reaction (PCR) expriments. however, most of these methods is time consuming to design optimal primers from large quantities of template DNA, and they are usually fail to provide a spesific size of PCR product. particle swarm optimization (PSO)has been applied to solve all kinds of problem and proved to be effective. in this paper, a piecewise linear chaotic map (PWLCM) is proposed to determine the value of inertia weight of PSO (PWLCP SO)to design feasible primers. the primer sets for homo sapiens RNA binding motif protein 11 (RBM11), mRNA (NM_144770), and homo sapiens tripartite motif-containinng 72 (TRIM72), mRNA (NM_001008274) were designed by PSO and PWLCPSO. five hundred runs were performed on differnt methods. A comparison of the results obtained from PSO and PWLCPSO primer design showed that PWLCM orovided better primer sets than PSO primer design.