The present invention provides an assessment method of a health state of a distribution primary device. The method comprises the steps of: establishing an index layered space model expressing a stateof a distribution primary device; performing normalization processing of the indexes, distribution of index weight values and determination of object elements to be assessed; and establishing a classical domain model and a joint domain model, and calculating an association degree value of the indexes and the state of the device. According to the technical scheme, the assessment method of the health state of the distribution primary device employs an object element extendable integration assessment method of an improved association degree function to perform information fusion, the assessment system is flexible in grade division, an assessment result of a single index is more refined, a device integration assessment result is accurate and concrete, the computing process is simple, and therefore, the assessment method of the health state of the distribution primary device is suitable for assessment work of the states of distribution primary devices with large installation quantity and wide installation areas.