Abstract: It is true that the second mover has the advantage over the first mover on certain condition. The single or multi-product growth pattern of imitative innovation project with R&D increasing was founded by analyzing the quantity relationship between the R&D input accumulation and project output. The contribution of the accumulation input of the R&D to the output of the imitative innovation project was specified. It was pointed out that the key of triggering second mover advantage over first mover was the continual R&D input. Especially, the continual and stable increase depended on the exploitation of the variety and series of the imitative innovation products.