Abstract: By applying real option game theory, an equilibrium price and optimal timing under the condition of nonperfect information for the controlling shares transfer were given, and the comparative static analysis was made for the main factors which affect the the optimal timing. The results show that, assuming other conditions remain unchanged, the better the quality of target companies, the smaller M and A sunk cost, the higher the percentage holding, the greater the expected synergies, the more low transfer price will result in the transfer of control sooner. The higher industry growth rate and the volatility, the faster the transfer of control, and there is a double effect.