As　optimal　performance　and　applicability　of　the　existing　production-distribution　planning　models　are　limited　in　a　distributed　decision-making　environment,　a　two-echelon　collaborative　planning　model　is　proposed　in　this　paper.　The　model　contains　planning　fields　of　the　buyer　and　the　supplier　and　considers　adjustable　delivery　quantities.　A　coordinative　process　based　on　Particle　Swarm　Optimization　(PSO)　is　designed　to　solve　the　model.　By　adopting　the　process,　the　optimization　can　be　achieved　and　only　partial　information　is　needed　to　be　shared.　Computational　experiments　show　that　the　model　and　algorithm　can　solve　the　problem　very　well　and　have　a　good　optimal　performance.