Spirulina platensis Geitler(SPG) has been proved as a multifunctional healthy food.The study was conducted by three different methods of administration in Ames test by us.TA98 was used as the testing strain.At a lower dose (40 mg/plate),SPG can inhibit the mutation effect of Aflatoxin B\-1(AFB\-1) when SPG and AFB\-1 were added into the reaction system simultaneously.When the mixture of SPG and AFB\-1 were added into the reaction system after a pre\|cultivation,the anti\|mutagenic effect can be observed at a higher dose (100 mg/plate) of SPG.These results showed that SPG has an inactivation effect to AFB\-1.\;It was found that SPG can not inhibit the mutation expression induced by AFB\-1.