Wind farms have been developed at both onshore and offshore sites to ease the global energy crisis in recent decades. Nevertheless, the differences between onshore and offshore wind characteristics and their wind energy potentials have rarely been studied. Based on two original sets of wind records respectively obtained from onshore and offshore wind measurement towers in southeast coastal region of China, this paper presents comparative evaluation for the onshore and offshore wind characteristics and their wind energy potentials in this region. The Weibull distribution function is firstly verified to be a reliable model for both onshore and offshore wind speed predictions. Furthermore, the variations of mean wind speed, Weibull parameters and wind power density are studied through monthly and hourly time scales. Finally, the economic feasibility for the wind turbine installations at the onshore and offshore site is examined in terms of the operating probability and the annual energy production (AEP) of a selected wind turbine. The results show that the offshore wind energy is more even and available than the onshore wind energy for the southeast coastal region. For the sake of economic feasibility and annual energy production, it is recommended to choose the hub heights of the selected wind turbine as 70 m and 40 m at the onshore site and offshore site, respectively.