[Objective] The spatio-temporal variability for inhomogeneity of intra-annual precipitation distribution was analyzed in order to provide the basis for regional water resource management. [Methods] Based on monthly precipitation data during 1970—2019 at 113 stations in He’nan Province, spatio-temporal variability of the precipitation seasonality index (PSI) was evaluated. [Results] ① The spatial distribution of PSI showed that North He’nan Province had higher precipitation inheterogeneity, and more than 28% of precipitation occurred in July; ② He’nan Province could be divided into four sub-regions with different temporal variations in PSI (west, central-east, north, and south areas) by using principal component analysis; ③ After 1990, PSI in west, central-east, and South He’nan Province showed a certain upward trend, while PSI in North He’nan Province showed a stronger short-term oscillation; ④ The interdecadal changes of PSI in most areas of He’nan Province were mainly influenced by ENSO; ⑤ The inter-annual fluctuation of winter wheat yield was more sensitive to PSI than the yield of other grain and oil crops. [Conclusion] The spatial-temporal variability of intra-annual precipitation distribution in He’nan Province was strong, and there were significant regional differences in the correlation between intra-annual distribution and large-scale circulation signals.