The Cosmology Large Angular Scale Surveyor (CLASS) is an array of telescopes to observe Cosmic Microwave Background (CMB) polarization in Chile. CLASS will make large angular scale CMB polarization measurements in frequency bands at 40 GHz, 90 GHz, 150 GHz, and 220 GHz. The CLASS survey (started from 2016) will constrain the tensor-to-scalar ratio from the first moments of the universe and also provide critical data on cosmic reionization, the sum of neutrino masses, and the Galactic interstellar medium. In this thesis, the CLASS strategy and design are introduced. The optical filter system is described in details along with two testing devices, including a Fourier Transform Spectrometer (FTS) and an optics test cryostat. For the telescope mount system, a bottom-up introduction is provided focusing on individual components. Preliminary data analysis from the first observing season with the 40~GHz telescope is also described
