The fatigue crack growth characteristics of base metal and weld joint of 9% Ni steel for LNG storage tank was carried out using CT specimen at room temperature and -162℃. Fatigue crack growth rate of base and weld metals at RT and -162℃ was coincided with a single line independent of the change of stress ratio and temperature. In the region of lower stress intensity factor range, fatigue crack growth rate at -162℃ was slower than that at RT, and the slop of fatigue crack growth rate at -162℃ increased sharply with propagating of fatigue crack, fatigue crack growth rate at RT and -162℃ was intersected near the region of 2x10-4 mm/cycle, and after the intersection region, fatigue crack growth rate at -162℃ was faster than that at RT. The micro-fracture mechanism using SEM shows the ductile striation in the stable crack growth region. Also the defects of weld specimen after fatigue testing were detected using the A scan of ultrasonic apparatus.