The difficulties of horizontal welding technology are stated in this paper. On the basis of analyzing the defects occurred during horizontal welding technology as well as several corresponding methods are adopted nowadays. Control measures for horizontal welding technology high efficiency can be summed up to two types: weld pool quick solidification control measure and weld pool stable shape measure. The development history of their research and application is reviewed. And the mechanism of producing weld defects is deeply analyzed. The prospects and development of horizontal welding technology are elaborated.