Through collecting water samples in the Lijiang River basin from September 2016 to June 2017, the main ions were analyzed. TTie control mechanism, sources and temporal and spatial variation characteristics of major ions in water chemistry of the Lijiang River basin were found. The results show that the pH value of the Lijiang River basin is between 6.89 and 7.79，with an average value of 7.34. Hie range of EC ranged from 70.6 to 385.5us·cm-1, with an average value of 228 us·cm-1. The range of TDS varies from 49.42 to 203.19mg·L-1, with an average value of 112.35mg·L-1. The concentration order of anion and cation is HCO3->SO42->NO3 ->CI- and Ca2+>Mg2+>Na+>K+, indicating that HCO3-Ca water is the main type. "Die variation characteristics of Ca2+, Mg2+ and HCO3- are similar, showing the characteristics of high middle reaches and low upper and lower reaches. The concentrations of Cl-, Na+ and K+ in the middle and lower reaches are higher than those in the upstream. Seasonal differences in the concentration of ions in the dry season are generally greater than in the rainy season. Ion source analysis shows that Ca2+, Mg2+ and HC03- are mainly derived from the weathering of carbonate rocks. Na+, K+ and Cl- are derived from the weathering of rocks, circulating salts also contribute a little to them. N03- and SO42- are also mainly derived from weathering and dissolution of rocks.