Abstract: Non-estrus of Sows causing sterile is a perplexing problem in raising pig produces. In order to know why sows are non-estrus deeply, special investigations were carried on in three cities in the north of Henan Province. Congenital factors, raising factors, breeding technology, climate, water and soil factors, disease and so on can all cause cows non-estrus. The reasons were classified and the investigation results shows: Raising factors account for 54.95%, congenital factors account for 6.5%, climate and water and soil factors account for 6.59%, breeding technology factors account for 4.3%, The disease factors account for 27.47%. The preventing and therapeutic methods were used correctly after the investigations. Integrated preventing and therapeutic methods can make sows non-estrus improve obviously.