A novel high-throughput spectrometer with a wide-slit is presented. In conventional spectrometers, the slit limited the light throughput. Here, the slit is replaced with a much wider one (200 μm) to increase throughput. A beam splitter is utilized to construct a dual-path optics to measure both non-dispersed and dispersed light intensity which comes from the wide-slit. While the dispersed light intensity is result of the non-dispersed light convoluted spectrum of the source, the spectrum can be acquired by solving the inverse problem of deconvolution. Experiments show that the reconstructed spectra achieved almost the same resolution measured by traditional spectrometer, while throughput and peak signal-to-noise ratio (PSNR) are improved dramatically.