Carbothermal reduction properties of low grade phosphate ore from Jinning,Yunnan were studied by kiln process.Four-factor and five-level orthogonal experiment was used to explore the influence of reaction temperature,reaction time,carbon excess coefficient,and Si/Ca ratio on the reduction rate of phosphate ore carbothermal reaction.The experimental re-sults showed that the order of factors influencing the phosphate ore reduction rate was as follows:Reaction temperature,carbon excess coefficient,reaction time,Si/Ca ratio.When the reaction temperature was 1 300 ℃,the carbon excess coefficient was 2.6,the reaction time was 1.5 h,and the ratio of n（Si）/n（Ca） was 1.5,the reduction rate could reach the highest value of 94.27%.Simultaneously,the applicability of Jinning,Yunnan low-grade mixed phosphate ore for kiln-process phosphoric acid production was evaluated,which showed that the mixed phosphate ore was suitable for kiln phosphoric acid production,and the research results had certain guiding significance for the low-grade mixed phosphate kiln process.