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Cosmic microwave background polarization on large angular scales contains distinct signals from the epoch of reionization and the primordial gravitational waves, offering promising avenues to probe the neutrino masses and inflation physics. However, ground-based measurements are plagued by atmospheric interference, making this task challenging. The Cosmology Large Angular Scale Surveyor, located in the Atacama Desert, Chile, is a multi-frequency telescope array (operating at 40, 90, and 150/220 GHz) designed to overcome these obstacles. Utilizing an innovative variable-delay polarization modulation technique and advanced detector technologies, CLASS aims to access the largest scale polarization modes. In this talk, I will describe its initial science release from the 40 GHz survey, which maps out 75% of the sky with linear polarization consistent with the Galactic synchrotron emission and places the tightest constraints on the astrophysical circular polarization background. This talk will highlight on the data pipeline development and the science results.