The oxygen isotopic compositions of whole rocks and single minerals were measured for alkaline granites from Nianzishan in Heilongjiang Province. The results show that the whole rocks and single minerals have widely variable δ18O values (-2.4‰～2.0‰for whole rock, 0.0‰～5.8‰ for quartz,-3.8‰～0.1‰for alkaline feldspar, and -8.5‰～-1.0‰for magnetite), and depleted in 18O. Oxygen isotope disequilibrium is observed between the coexisting minerals, indicating water-rock exchange for the alkaline granite during its emplacement.The initial δ18O values of rock and external fluid are estimated according to the oxygen isotopic compositions of rnzircons and modern meteoric water. Quantitative simulation was carried out by using the kinetic model of oxygen isotope exchange between multi-minerals and water. It is obtained that the flow rate of fluid is about 1×10-15～3×10-14 mol/s , the time of water-rock interaction is about 0.3～3Ma, and ratio of water to rock is about 0.11～1.02. Significant decrease in quartz δ18O is ascribed to water-rock interaction of higher temperatures (～400℃) rnand longer time (＞1Ma).%对黑龙江碾子山碱性花岗岩的全岩及其主要单矿物进行了氧同位素分析。结果表明，全岩和单矿物不仅δ18O值变化范围较大(全岩-2.4‰～2.0‰，石英0.0‰～5.8‰，碱性长石-3.8‰～0.1‰，磁铁矿-8.5‰～-1.0‰)，而且强烈亏损18O。共生矿物之间表现出明显不平衡的氧同位素分馏特征，指示在花岗岩侵位之后与水之间发生了同位素交换。根据锫石和现代大气降水的氧同位素组成，对岩石与外来流体的δ18O值进行了估计。多维矿物相-水氧同位素交换反应动力学模型定量模拟表明，碾子山岩体流体流动速率约为1×10-15～3×10-14mol/s，水-岩反应时限约为0.3～3Ma，水/岩比(氧摩尔比)介于0.11～1.02之间。水-岩反应温度较高(约400℃)和反应时间较长是导致石英δ18O降低的主要原因。
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