Phosphorus content is an important index to measure the quality of comparism fertilizer. Both GB/T 8573-2017 and GB/T 15063-2020 are commonly used for the determination of phosphorus content in compound fertilizers. This paper compared the difference in phosphorus content between the determination results using the two methods，showed that the test results were within the allowable range，the accuracy was good and there was no significant difference in the results between the two different methods. For the determination of water-soluble phosphorus content，the precision of ultrasonic extraction-gravimetric method is better than that of water-grinding and gravimetric method，and the time consuming is shorter. For the determination of available phosphorus content，EDTA heating micro-boiling gravimetric method is simpler，faster，more efficient and suitable for mass detection. In addition，the key points in the experiment are discussed in order to get higher accuracy of data results.