The process of the magnetic polarity reversal of the Sun has been an important subject in the solar physics. The objective of this study is to investigate how solar global magnetic field change over solar cycle by tracking the migration of open magnetic flux regions. The results show that the open magnetic fluxes migrate from one pole to the other crossing the equator during a solar cycle. The migration rate is approximately 10 m s-1, comparable to meridional flow. The results have been published in Scientific Reports (Huang et al. (2017)).