Abstract: The aim of this article was to exploring optimal method of testing the free amino acid of Chinese olive.The conditions of Ninhydrin Colorization method, such as p H, chromogenic agent content, heating temperature and heating time, were selected through single factor experiment, and through the methodology experiment included stability test, exactness test, repeatability test and sample recovery test to verify it. The results showed that the optimal reaction conditions of Ninhydrin Colorization method, such as the maximum absorption wavelength was 568 nm, the optimal p H of phosphate buffer was p H6.6, the optimal content of 2% chromogenic agent was 0.5 m L, the optimal heating temperature was 100 ℃ and the optimal heating time was25 min. The methodology validation results showed that the OD was change 0.41% in 30 minutes, the stability of RSD was equal to 0.34% ( n = 9) , the exactness of RSD was equal to 0.09% ( n = 9) , the repeatability test of RSD was equal to 1.71% ( n = 6) , the sample recovery test of RSD was equal to 2.21% ( n = 6) and the recovery rate was 100.34%. It stated that Ninhydrin chromogenic method of testing free amino acids for Chinese olive was feasible, and it performed very well in the area of the stability, the exactness, the repeatability and recovery rate under this condition. Therefore the method was suitable for testing free amino acids for Chinese olive quickly and easily.