The invention discloses a ring main unit cable core temperature soft measurement method based on a neighborhood preserving embedded regression algorithm. The ring main unit cable core temperature soft measurement method comprises that firstly, based on the local feature extraction strategy of the neighborhood preserving embedded algorithm, a regression optimization function which takes the internal temperature and the internal humidity of a ring main unit, the cable core current and the cable surface temperature as input, and takes the cable core temperature of a cable in the ring main unit as output is established, local features of input data and output data are reserved, and the maximum relationship between data is obtained; then based on lower-dimension latent variables of data, input and output features which construct data regression are obtained; and a cable core temperature soft measurement model is established. The ring main unit cable core temperature soft measurement method is advantaged in that by means of a data local feature extraction method, a traditional neighborhood preserving embedded algorithm is modified to be a regression model, and key variable information, of the ring main unit, which cannot be measured easily is obtained. According to the invention, the problem that the temperature of the cable core in the ring main unit cannot be measured easily is solved, and the accuracy and operability of on-line monitoring and fault locating of the ring main unit are improved.