Variation of δ18O in precipitation is a physical process of evaporation and condensation and closely related to various factors, such as latitude, altitude, distance from coast, seasonal variation and precipitation amount, and have characteristics of regular change. According to isotope data in precipitation and meteorological data obtained from upper, middle and lower reaches of the Yellow River Basin, spatial and temporal variation characteristics of isotope in precipitation was analyzed. The relationship between stable isotopes in precipitation and temperature, as well as precipitation amount, reveal the changing regularity of stable isotopes in precipitation over the Yellow River Basin. The results indicate that the seasonal variations of stable isotopes in precipitation have different features in the upper, middle and lower reaches of the Yellow River Basin, with enrichment of stable isotopes in summer and depletion in winter for the upper reaches, and opposite features present in the middle and lower reaches. The spatial distribution shows that stable isotopes in precipitation tends to decrease from upper reaches to lower reaches generally, with significant fluctuation and the extremum area. Different reaches of the Yellow River have different isotope process, and the altitude effect and circulation of internal continent affect stable isotopes in precipitation significantly in the upper reaches, while stable isotopes in the middle and lower reaches are influenced by monsoon system and local factors. Analysis of local meteoric water line and correlation of d excess in precipitation with vapor pressure suggests that rainfall events undergo secondary evaporation accompanied by isotope fractionation during rain drops descent from the cloud base to the ground.