With the development of high voltage direct current transmission system, the new large-capacity synchronous condenser has become the best choice to meet the dynamic reactive power demand of the system. Therefore, it has gradually become one of the research hot topics. Based on this, this paper systematically summarizes the research status of the new type of the condenser. Firstly, the operation principle of the condenser is introduced from three aspects: its mathematical model, operation state and control strategy. Secondly, by comparing it with power electronic reactive power compensation equipment, the superior dynamic reactive power output characteristics of the new condenser are expounded, and their influence factors are analyzed. Finally, the latest development of the state monitoring technology of the condenser is summarized from both the existing fault diagnosis technology and parameter identification technology of the condenser. In this paper, the mathematical model, control strategy and operation state monitoring of the new synchronous condenser are summarized, which can provide reference for the further research of the new synchronous condenser.