Alfvn waves are ubiquitous in the solar wind and have important implications for the plasma heating and acceleration. The advances in Alfvn wave research in the solar wind in recent years are summarized from the aspects of solar wind structures, solar wind turbulence, global models of the solar wind, plasma instabilities (the parametric decay instability and firehose instability), and the solar wind heating and acceleration. In view of the current research trend, the future research of Alfvn waves is foreseen in three directions: the sub-Alfvnic solar winds, global models of the solar wind and solar source regions.