In this paper, we intend to explore the impact of spillover effect on technological choice of flexible-manufacturing-systems(FMS). Build on Tseng (2004), we set up a two-stage game of duopoly in which all firms invest for R&D with spillover effects andearn profit from delivering commodity. We find that the firm produces its outputs at shorter expected delivery time and obtain thehighest market shares if spillover effects exist among two firms. In addition, the fleet changes of uncertain consumer preferencemake firms choose more flexible manufacturing technologies for avoiding the loss of slow delivery.