The invention discloses a distribution network safety evaluating and early warning method after large scale distributed photovoltaic grid connected; influences against the power distribution network after distributed photovoltaic power generation system grid connected are studied in various angles like maintenance safety and electric energy quality; quantification indexes representing influences, caused by distributed photovoltaic grid connected, against the power distribution network in power grid loss, electric energy quality, reliability and environment aspects are provided; distributed photovoltaic grid connected operation reliability and security are systematically evaluated by a method combining DC evidence theory with an association analytical method; real time monitoring and analyzing are carried out for distributed photovoltaic grid connected common connection points, thus realizing safety grade evaluation and safety early warning for each distributed photovoltaic grid connected; the method can provide important basis for distributed photovoltaic grid connected power generation operation control and examine evaluation, thus improving state grid company safety operation management capability for distributed photovoltaic power generation, and distributed photovoltaic power generation large scale grid connected can be implemented.