Abstract: Although at present the relevant National Standard stipulates to use potassium tetraphenylborate gravimetric weight method to determine potassium content in all potassium fertilizers，there are differences in aspects of washing of precipitate and so on， according to the different Standards of potassium chloride，potassium sulfate，and various kinds of potassic complex fertilizers.The experiments with different washing methods for measuring the potassium oxide content in potassium chloride have been compared.It was found that there is a certain disparity in precision when applying the existing Standard of potassium chloride and there are also shortcomings in actual operation.Therefore，it is proposed that to replace the measuring method of potassium chloride′s potassium content with the method of potassium sulfate applied.Besides，in order to improve the production control of potassium fertilizer，a new titration analysis method for potassium content has been put forward，which is less time-consumed and convenient for instant analysis and control during the production.