The invention relates to a measuring method of the content of boron elements contained in an aluminium-titanium-boron alloy, which measures the content of the boron elements contained in the aluminium-titanium-boron alloy by a photoelectric direct-reading emission spectrum method. The method also enables an analysis line to have a better linear relation with spectral intensity and the mass fraction of the boron elements within a detection range by selecting a proper boron element spectrum line as the analysis line and an aluminium base characteristic spectrum line with little interference as an inner marking line so as to establish a working curve detecting the boron content, thus the direct accurate measurement of the boron elements contained in the aluminium-titanium-boron alloy within the certain detection range is realized; the invention also optimizes the excitation parameters of a photoelectric direct-reading emission spectrometer; and in addition, the measuring method has fast analysis without resolving a sample and easy operation and is very suitable for the process control detection and the finished product detection of a production line.