Based on the resource-based theory and dynamic capability theory, the acquisition of innovative value in the diversity of alliance portfolio was studied by questionnaire. The relationship between alliance portfolio diversity and the focal firm innovation performance was discussed, then the mediating role of search routine and the moderating role of social capital in the relationship were analyzed. The results show that alliance portfolio diversity has an inverted U-shaped relationship with the focal firm innovation performance; search routine mediates the diversity of alliance portfolio -focal firm innovation performance relationship; both structural social capital and relational social capital strengthen the inverted U-shaped relationship between the alliance portfolio diversity and search routine, and the mediating effect mentioned above; relational social capital plays a more stronger role in the two moderating effects especially.