This paper examines the destination choice of migrants from a cost-benefit perspective, using binary logit models to explain why the megacities are so popular to be their destination. The results show that the net revenue, particularly different wage levels the floating individuals expect has great impact on their destination choices, which validates an important fact that high-wage income or that the huge wage gap between different regions is an important reason why migrants flowing into megacities. The total expenditure of floating migrants in Beijing, Shanghai and Guangzhou does not inhibit their flowing into these large cities. Implications of the results are that rather than taking measures to raise the cost of living in the cities to limit the floating population, it is better to make efforts in developing neighboring regions to attract more enterprises, create more jobs, and improve public services, thus redirecting the migrants in choosing their destination.