Abstract: Spectrum-tunable light source is an integrating sphere source illuminated by a large number of LEDs with different spectral peaks and distributions. The spectral matching algorithm is an essential approach to produce varieties of spectra. Levenberg-Marquardt algorithm was proposed and a series of simulations using Gaussian curves with an equal interval were conducted. The results of simulations show that Levenberg-Marquardt algorithm can make spectrum-tunable source produce solar, dessert,ocean and vegetation spectrum, respectively, the relative spectrum differences are 2.17% , 1.76% , 2.03% and 1.7%,respectively. The validating experiment for a number of target distributions was performed, and the relative spectral differences are all no more than 5%. The experiment verifies that it is feasible to produce different spectral distributions by using Levenberg-Marquardt algorithm for spectrum-tunable integrating sphere light source.