The technological activities in early POSCO focused on technological acquisition from advanced countries. The prime route of POSCO’s technological acquisition was overseas training. Japan Group cooperated well with the transfer of operation technology but not the case of computation and quality control. In the course of overseas training, POSCO men not only actively participated in formal courses but also checked daily training by collaborative discussion and mobilized informal technological learning mechanism. Acquired technology was more articulated by the factory operation. Mock operation training was effectively enforced, practical know-how and trouble-shooting capability was quickly secured through real operation. Consequently, the period to normal operation was very shortened and yield ratio in all sectors was continuously improved.