With the rapid development of network technology and digitaleconomy, the scale and influence of Internet platforms have been expanding,and great market power is in the hands of individual Internet platforms.As Internet platforms are characterized by bilateral markets, cross-networkexternalities, and asymmetric pricing structures, leading to more frequent abuseof market dominance than other traditional industries, it is crucial to curb theabuse of market dominance by Internet giants through the antitrust mechanism.This paper analyzes the concepts of dominant market position and relatedmarkets, combines the characteristics of Internet platforms, discovers the causesof the abuse of dominant market position by Internet platforms, analyzes therelevant cases of the application of administrative penalties for the abuse ofdominant market position, researches the problems on its predicament, andputs forward relevant suggestions to promote the improvement of the antitrustsystem of Internet platforms.