Strategy selection is a fundamental problem for the evolutionary game process in structured populations. This paper aims at investigating the strategy selection problem by introducing a continuous evolutionary game dynamics on complex networks. It is shown that the population preference for strategies keeps unchanged under random drift in the evolutionary process. However, because of selection, the population will favor one strategy over the other based on the population structure and game payoffs. In particular, for the prisoners dilemma game, our results show that the cooperation is never favored in complete networks. However, it is greatly promoted by cycle networks. The above results are consistent with those in the traditional discrete evolutionary game dynamics. It should be especially pointed out that the proposed framework provides a potential effective tool for analyzing and controlling the evolutionary process in populations.