Abstract: In order to find out a fast, simple and reliable detecting method, the content of K in potato was detected by using flame method and TAS-986 atomic absorption spectrophotometer. Results showed that the correlation coefficient （R2） of standard curve was 0.990 0, and the average recovery was 91.58%, and the precision and repeatability （RSD） was less than 10%. Therefore, the determination method of K content in potato had some advantages of reliability, high precision, good repeatability and high recovery.