The FAST cable net structure of the National Astronomical Observatory is the support and angle adjustment mechanism of the whole system. It has been under the action of reciprocating loads with variable amplitude and unequal stress levels during the working phase. The stress relaxation, deformation and fatigue of the cable will affect the entire FAST structure. The redistribution of cable force and the change of Morphogenesis of the reflector will affect the overall stability of FAST. Especially in the years after completion, its changes are more significant. Therefore, the National Astronomical Observatory project has put forward very high technical requirements for cable network construction. According to the strict technical standards for cable network construction, a 500MPa ultra high stress amplitude cable has been developed, and high-precision cables and node plates have been manufactured using new processes. The construction process of "1/5 rotational symmetry, large-span cable net high-altitude loose assembly" was proposed on site, and the cable net installation work was successfully completed