Net primary productivity (NPP) of terrestrial ecosystem is of great importance to the sustainability of human being, thus, its response to the changing climate becomes a research focus.Observation, experimentation and simulation are three interrelated methods used to address this issue.Strong progress has been made, whilst many uncertainties still exist. The progresses in this field is reviewed. It also pointed out that, great effort should be made to collect systematic and long-term ecosystem data, to conduct experiments at the whole ecosystem level and to develop dynamic global vegetation model(DGVM),etc.