The space mission of Lagrange-V solar observatory （LAVSO） proposed by Nanjing University，China Meteorological Administration，and Shanghai Academy of Spaceflight Technology，which is also dubbed as “Xihe-2”，will be the first man-made probe to be launched to the fifth Lagrange point of the solar-terrestrial system.It aims to precisely measure the vector magnetic fields，reveal the three-dimensional solar eruptions and provide accurate warning and forecasting of solar activities，and thus answer the two important scientific and application problems in the fields of solar physics and space weather，i.e.，“the generation and evolution of solar magnetic fields and their connections with the solar eruptions” and “the propagation of solar eruptions and their relationships with the hazardous space weather”.In this paper，the scientific and application objectives，payloads，and preliminary plans of “Xihe-2” are overviewed.With the solar observations in the Sun-Earth direction，the implementation of “Xihe-2” will usher in the era of China’s solar stereoscopic observations，expand human’s understanding on the mechanisms of solar eruptions，and bring revolutionary breakthroughs in the research of space weather.