加速器质谱法（Accelerator Mass Spectrometry, 简称AMS），是一种质谱分析方法，与其他的质谱分析方法不同，加速器质谱法将离子加速到非常高的速度，再进入质谱分析单元从而提高了质谱的灵敏度和辨别度。加速器质谱法在分离放射性同位素和其丰度高的其它同位素上很有意义，如从C中分离。这一方法可以通过剥离来完全排除分子的同质素和大部分原子同质素，比如排除N对C的影响。这一方法可以用于检测自然界存在的半衰期较长的同位素比如Be、Cl、Al和C（丰度在10到10）。

Accelerator mass spectrometry (AMS) differs from other forms of mass spectrometry in that it accelerates ions to extraordinarily high kinetic energies before mass analysis. The special strength of AMS among the mass spectrometric methods is its power to separate a rare isotope from an abundant neighboring mass ("abundance sensitivity", e.g. C from C). The method suppresses molecular isobars completely and in many cases can separate atomic isobars (e.g. N from C) also. This makes possible the detection of naturally occurring, long-lived radio-isotopes such as Be, Cl, Al and C. Their typical isotopic abundance ranges from 10 to 10. AMS can outperform the competing technique of decay counting for all isotopes where the half-life is long enough.