Aluminum is concerned as a possible cause of many diseases. To investigate the long-term Al biokinetics and bioavailability in various kinds of Al-contained medicine and food, an accelerator mass spectrometry (AMS) based on the HI-13 tandem has been established for biological analysis with 26Al (T 1/2 = 716,000 years) as the tracer. In this paper, the animal tracing, sample preparation procedure and 26Al-AMS measurement are presented. The sample preparation procedure has been simplified. A high sensitivity of 5 × 10−15 for 26Al/27Al has been achieved. Two phases were found before and after a break time (t b) for the 26Al retained in blood and brain, with t b ≈ 8 and 12 h after the 26Al tracer injection, respectively.