With the continuing rapid increase of the installed capacity of the wind farms and the construction of the large-scale wind farms, utilities in every country have proposed more strictly grid codes for the wind farms. This paper will make a detailed instruction of the low voltage ride through (LVRT) requirement for the wind farms, based on the rules for the wind farms accessing to the power system. It will also make a comprehensive analysis and comparisons of the technologies to meet the LVRT requirements for the doubly-fed induction generator (DFIG), which is used universality. In the end, it will make an improvement of the technologies and come up with the future research direction.