Abstract: Pulsed magnetic flux leakage testing is a new magnetic leakage flux nondestructive testing method which regards the pulse signal as an excitation source. Recently it has been widely used in the testing of ferromagnetic materials such as steel to promise the security of production and transmission, so that the economic loses can be cut down. In this paper, a pulsed magnetic flux leakage testing method based on hall sensor is proposed and a system of pulsed magnetic flux leakage testing is built up. Furthermore, a testing platform based on Labview is designed to collect magnetic flux leakage signals of the crack defects by sensor under pulse excitation. Several plate samples with different machining crack defects are tested through experiments. In the experiment, quantitative estimations of width and depth parameters of crack defects based on peak values and peak-peak values of the detected signals are conducted.