In order to control the content of hydrogen in aluminum melt, the principle and characteristics of various on-line methods for measuring the content of hydrogen in aluminum melt, such as vacuum solidification method, first bubble method, inert gas cycle method and hydrogen concentration difference cell method, were reviewed respectively according to the different operation methods. Various on-line hydrogen measurement methods were compared and analyzed in terms of operation mode, test results, test time and cost. The development direction of on-line continuous hydrogen measurement technology is mainly to extend the service life of high-temperature hydrogen measurement probe and reduce the overall cost of the device.