Abstract: This article presents a technique to restore X-ray bremsstrahlung spectrum. Through restoring the bremsstrahlung spectrum of the imploded capsule, we can obtain the information of the pellet. Assuming the energy density in each energy band is equal, we divided the energy range into 5 parts, and with a specially-made multi-pinhole camera and an algebraic transformation, we recorded images of the hot-spots. The images were produced on the imaging plate. In this way, five different linear equations were obtained and through this equation group, we could restore the spectrum. This approach was applied to hot-spot bremsstrahlung spectrum reconstruction of Shenguang Ⅲ prototype Facility. Based on the spectrum reconstruction, we deduced the temperature of the hot-spot, which is in line with the result obtained from the characteristic spectral line of the tracer element.