Based　on　the　analysis　of　the　basic　Particle　Swarm　Optimization　(PSO),　a　PSO　with　local　interpolation　search　(PSOlis)　is　proposed　with　interpolation　methods.　The　improved　PSO　takes　full　advantage　of　the　best　location　of　individual　particles　and　the　better　position　among　particles　to　modify　the　best　location　of　the　individual　particles.　The　experiments　with　test　functions　show　that　PSOlis　has　better　convergence　accuracy　and　faster　convergence　speed　than　the　basic　PSO.