Combining laser heterodyne with linear frequency modulated technology, based on the measurement method of magnetostrictive coefficient, a novel method of linear frequency modulated multi-beam laser heterodyne measurement for magnetostrictive coefficient was proposed, which converted the measurement of magnetostrictive coefficient into the length variation. Based on linear frequency modulated technology, the information of length variation was loaded into the frequency difference of the multi-beam laser heterodyne signal, and many value of length variation could be acquired simultaneously after the multi-beam laser heterodyne signal was demodulated. Processing these values by weighted-average, length variation could be obtained accurately, and eventually the accuracy of magnetostrictive coefficient was improved. The magnetostrictive coefficient of the sample under different currents was simulated by Matlab. The results indicate that compared with traditional technique, the relative measurement error of this method is less than 0.09% and the accuracy is improved more than one order of magnitude.