A method for obtaining a flicker transmission coefficient of grid connection of photovoltaic power stations, comprising: establishing an equivalent circuit diagram of grid connection of a photovoltaic power station group; forming a multi-port network diagram for the photovoltaic power station group by transforming voltage fluctuation generated by the grid-connected photovoltaic power station group into a equivalent fluctuating current according to Norton's theorem and injecting the fluctuating current into a network; obtaining sub-transient reactance of a synchronous power generator from parameters of the synchronous power generator, obtaining sub-transient reactance of an induction motor from parameters of the induction motor, obtaining sub-transient reactance of a photovoltaic converter from parameters of the photovoltaic converter, and obtaining static load equivalent impedance from static load (S 13); obtaining a node impedance matrix of a multi-port network by using the sub-transient reactance of the synchronous power generator, the sub-transient reactance of the induction motor, the sub-transient reactance of the photovoltaic converter and the static load equivalent impedance as ground impedance of a respective node in conjunction with the multi-port network diagram and line parameters (S 14); obtaining an inter-harmonic voltage component of a node in the multi-port network based on the node impedance matrix and an inter-harmonic current component of the photovoltaic power station group (S 15); obtaining a fluctuating voltage of the node by superimposing the inter-harmonic voltage component of the node on a fundamental wave component of the node; obtaining effective value voltage fluctuations at different inter-harmonic current frequencies of the node based on the fluctuating voltage of the node (S 17); and obtaining a flicker transmission coefficient between any two nodes by calculating a ratio of the effective value voltage fluctuations of the two nodes in the multi-port network. establishing an equivalent circuit diagram of grid connection of a photovoltaic power station group; forming a multi-port network diagram for the photovoltaic power station group by transforming voltage fluctuation generated by the grid-connected photovoltaic power station group into a equivalent fluctuating current according to Norton's theorem and injecting the fluctuating current into a network; obtaining sub-transient reactance of a synchronous power generator from parameters of the synchronous power generator, obtaining sub-transient reactance of an induction motor from parameters of the induction motor, obtaining sub-transient reactance of a photovoltaic converter from parameters of the photovoltaic converter, and obtaining static load equivalent impedance from static load (S 13); obtaining a node impedance matrix of a multi-port network by using the sub-transient reactance of the synchronous power generator, the sub-transient reactance of the induction motor, the sub-transient reactance of the photovoltaic converter and the static load equivalent impedance as ground impedance of a respective node in conjunction with the multi-port network diagram and line parameters (S 14); obtaining an inter-harmonic voltage component of a node in the multi-port network based on the node impedance matrix and an inter-harmonic current component of the photovoltaic power station group (S 15); obtaining a fluctuating voltage of the node by superimposing the inter-harmonic voltage component of the node on a fundamental wave component of the node; obtaining effective value voltage fluctuations at different inter-harmonic current frequencies of the node based on the fluctuating voltage of the node (S 17); and obtaining a flicker transmission coefficient between any two nodes by calculating a ratio of the effective value voltage fluctuations of the two nodes in the multi-port network.