Search for Terrestrial Exo-Planest (hereafter STEP) mission is a latest advanced research project in Chinese Strategic Pioneer Program (SPP) on Space Science. STEP aims at the nearby earth-alike planets detection, comprehensive research on the planetary system and some astrometry research under 0.5 uas precision in the space, which will get the fruitful achievements in the exo-planetary and astrometry research fields. STEP will take the Space Astrometry technique in the optical band. The FOV is 0.44 degree, based on 1.2m primary and focus length is 50m. The special metrology technique will be taken to reach 0.5 uas astrometry precision, which will be ideal for terrestrial exo-planets detection. The goal of the Seminar is to explore the scientific goals of the STEP mission, key technologies and future collaborations, discuss the layout of the research or project dividion in the next two years. And to produce a summary report of the discussion for the reference of the Space Science Committee and STEP team.