The invention provides a power grid earthquake early warning method and system. The earthquake early warning method is based on a earthquake monitoring point arranged in a transformer substation, andearly warning information is sent through an internal communication network of a power grid or an intelligent electric meter. The method comprises the following steps: acquiring the seismic waveform data by a seismic monitoring point, and extracting the characteristic values of the seismic waveform data to be sent to a seismic early warning data center; and then conducting earthquake speed judgment by the seismic early warning data center according to the characteristic values to obtain speed judgment information, and issuing the speed judging information to an early warning information receiving object according to a preset range and a preset mode. According to the invention, the seismic early warning technology can be fused with an intelligent power grid technology, and the anti-seismicemergency capacity of the power grid can be enhanced, meanwhile, the operation and maintenance of the seismic monitoring points are facilitated, and the huge economic and social values of the seismicearly warning technology are achieved.