Our understanding for high-mass star formation is much less than for low mass ones.The difficultiesof probing high mass star formation not only come from the large distance and complex regions,but also fromthe feedback during their formation.The strong radiation pressure of a forming star with 8 M⊙ can haltspherical infall,preventing its further growth.Than two major theoretical models on the further growth ofsuch stars were proposed.One suggests the mergence of less massive stellar objects,and the other is stillthrough accretion but with the help of disk or outflow.Inflow motions are the key evidence of how formingstars further grow.Recent development in technology has boosted the search of inflow motion.A number ofhigh-mass collapse candidates were obtained with single dish observations,which were confirmed with highresolution observations.Results seem to favor the accretion model.However there are still fundamentaldifference between low-and high mass star formation.Currently the collapse signature evolutional tendencyis opposes the theoretical prediction and very different from that of low – mass star formation.Infall motiontaking place from outside-in or on the contrary is inconclusive from the current observations.The directevidence for the collapse processes is in monolithic or in competitive deeds to be searched.And the initialconditions of collapse are not clear.Future work is also needed to distinguish among infall,rotation andoutflow regions,and to establish the observational picture of the improved accretion model.