The invention relates to a power transformer fault early warning system based on data mining, and the system comprises a power transformer full-dimension original data set module, a seamless embedded data application interface module, a power transformer full-dimension original data set cleaning module, a power transformer high-quality sample data set module, and a power transformer core algorithm module. a power transformer fault early warning model analysis module, and a human-computer interface display module. Compared with the prior art, the system has the advantages that massive electric power big data generated in intelligent power grid construction is fully utilized, implicit and potential value information is extracted by adopting a data mining method, the modeling speed is high, the learning process is simple, and a complete fault knowledge base is not needed; the defects of low modeling speeds, low accuracy and the like of traditional modeling methods are overcome, the problems of low maintenance pertinence, incapability of distinguishing primary and secondary maintenance, rigid maintenance mode and the like in planned maintenance of the power transformer are solved, and the requirement of fault early warning of the power transformer is met.