Abstract: Large-scale photovoltaic grid-connection makes the security of power grid increasingly prominent. Accurate power prediction can provide reliable data support for the stable operation of power grid. At present, a lot of research has been carried out on the ultra-short-term prediction of PV at home and abroad, whereas its prediction accuracy needs to be further improved. Therefore, the paper summarizes the four aspects such as influencing factors, research methods, prediction difficulties, and future development trend. Firstly, the influencing factors and forecasting methods of photovoltaic power generation are summarized. Then, on the basis of in-depth analysis of historical power data prediction method, data prediction method considering future meteorological factors, cloud observation data prediction method and a variety of data combination prediction method, the existing technical difficulties are sorted out. Finally, the prospects in future research directions of technology are put forward.