Based on the enterprise managers' cognition of brain, the network game model of R&D investment for generic technology is proposed firstly, in which enterprise utility is consisted of ego utility and network utility. The ego utility comes from the impact of the generic and private technology on enterprise itself; The network utility of enterprise comes from the spilled utility of its adjacent enterprises along the enterprise social network which is determined by the altruism of the managers' brain cognition. Then, the best response function is constructed based on managers' altruistic cognition of brain by individual decision-makers, and the Nash equilibrium is also given; Some discussions are presented including the Pareto equilibrium for social decision-making, the impact of managers' brain cognition though social network on generic technology R&D investment. Finally, some simulations have been done for two types of networks and two different brain cognition weights on network game respectively. It is found that, regardless of the existence or absence of enterprise social networks, the voluntary supply of generic technology R&D investment is not enough due to the lack of altruistic brain cognition of managers, but the social network has a positive impact on voluntary supply. It is also found that the modular structure of "small world" in the network and the network shortcut can induce managers raising awareness of altruism and the voluntary contribution to the generic technology R&D investment. The conclusions have proposed a feasible path to increasing generic technology investment though raising mangers' brain cognition.