The invention discloses a method and device for establishing a distributed power source planning mathematic model. A comprehensive evaluation index planning adaption function is constructed accordingto a planning adaption function and a scene occurrence probability, the adaptation of the planning scene under the random environment is assessed from the angle of the probability, and a planning model is established based on the above method. The technical problem that distributed power source can play the deterioration effect when being operated under some conditions since the planning method according to nominal output in the prior art cannot guarantee the power distribution network of the distributed power source to satisfy various operation constraint conditions in the operation is solved.