The solar wind turbulence was found in the early days of spacecraft observations. Although many international scientists studied on this topic for many years, the nature of the solar wind turbulence had not yet been discovered till the middle of 1980s. The solar wind turbulence is different from the fluid turbulence. Many observations could not be explained by the previous theory. Tu Chuanyi et al^［1~5］pointed out that non-linear turbulent interactions exist in the solar wind fluctuations. However the solar wind turbulence is not a developed turbulence. It is in a state of transition from Alfven waves to developed turbulence. This new idea combined the Alfven wave propagation theory with the turbulence transfer theory and led to a few theoretical development, which discovered the nature of the solar wind turbulence and explain several important observations.