Critical micelle concentration (CMC) was a vital physical character of bayberry tannin (BT).In this paper, CMC of BT was determined by pH method .The jump of H +concentration before and after the formation of BT micelle was investigated to obtain the CMC by plotting a graph of pH against CBT.Furthermore, influence factors of CMC were also investigated.The result showed that CMC of BT was 1067.9mg/L at the temperature of 303.0K, and the CMC was influenced by solution temperature , kind and usage of inorganic ions.Along with the rise of solution temperature , CMC decreased first and then increased .A minimum value of 1062.0mg/L was determined at 313.0K.Meanwhile, CMC also decreased after additions of Na +and Ca2+into BT solution, respectively.And the CMC was 891.4 mg/L after adding Ca2+which was lower than that of Na +for the higher charge of Ca2+.The CMC of BT was 897.5 mg/L and 891.4 mg/L respectively after adding Na +and Ca2+with the same amount.(10 mmol/L, the temperature of 303.0K).%杨梅单宁（ bayberry tannin ，BT）的临界胶束浓度（ CMC）是杨梅单宁溶液的一个重要物理参数。实验利用pH法测定水溶液中杨梅单宁分子形成胶束形态前后H＋浓度的突跃，以pH-CBT做图测定杨梅单宁溶液的CMC值，并且探讨杨梅单宁溶液CMC值的影响因素。结果表明：303．0 K时杨梅单宁的CMC值为1067．9 mg/L，且该值受溶液温度、无机离子种类与用量的影响；CMC值随温度升高呈现先减小后升高的趋势，313．0 K时降低为1062．0 mg/L；Na＋和Ca2＋的加入使CMC值降低，且由于Ca2＋比Na＋所带电荷量更大，造成CMC值更低；303．0 K时加入相同用量（10 mmol/L）的Na＋和Ca2＋，使杨梅单宁溶液的CMC值分别降低为897．5 mg/L和891．4 mg/L。
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