The invention discloses a distributed photovoltaic installed capacity prediction method based on investment return rate. The distributed photovoltaic installed capacity prediction method comprises the following steps: determining roof resource state in a certain area; determining photovoltaic resource development potential in the area; establishing a distributed photovoltaic generating project benefit analytic model; predicting the distributed photovoltaic project annual investment return rate according to real-time market classification; utilizing the linear regression analysis method to establish a relationship model of the project annual investment return rate and the distributed photovoltaic popularizing rate; predicting the distributed photovoltaic installed capacity through the popularizing rate according to the roof resource state. Based on distributed photovoltaic project investment return rate, the distributed photovoltaic installed capacity prediction method, provided by the invention, fully complies with a current photovoltaic market mechanism, provides a new prediction method by taking photovoltaic as a new energy, fills in the gap of prediction of distributed energy, and provides reference for consideration of electric grid planning of distributed power supply.