The essence,significance and relationship of Polybasic Acid or Polybasic Base titration conditions were revealed with the titration curve.The findings showed that:Ki/Ki+1 is the determining factor of stepwise titration and the primary indicator that influences the titration j ump;while cspi Ki is the key which determines the j ump value when Ki/Ki+1 is enough large.The decision procedure of before-titration is:first,to determine whether the Ki/Ki+1 of the measured obj ect is greater than or equal to 105 ,so as to see whether the stepwise titration is applicable;then it is to determine whether cspi Ki is greater than or equal to 10-9 ,so as to see whether accurate titration can be directly applied under the current conditions.%结合滴定曲线,系统揭示了多元酸碱滴定条件的本质、意义和关系。研究表明：Ki/Ki+1既是分步滴定的决定性因素,也是影响滴定突跃的首要指标；cspiKi 是当Ki/Ki+1足够大时,决定突跃大小的关键所在。滴定前的判定程序是：先看被测物的Ki/Ki+1是否大于或等于105,以确定能否分步滴定；再看cspiKi 是否大于或等于10-9,以确定现有条件下能否直接准确滴定。
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