A distributed photovoltaic grid-connected acceptable capacity calculating method based on improved Big Bang-Big Crunch. The distributed photovoltaic grid-connected acceptable capacity calculating method based on the improved Big Bang-Big Crunch comprises the steps of basic data acquisition, model building, algorithm parameter initialization, initial fragment solution generation, fitness evaluation, gravitational solution generation, explosion iteration cycle, cycle termination judgment and the like. According to the present invention, modeling is carried out on the problem of the maximum accessibility capacity of distributed photovoltaics in a power distribution system fro the angle of planning of a power distribution network so as to establish a grid-connected photovoltaic maximum accessibility capacity model which uses the distributed photovoltaic access capacity maximization as a target function and uses a system power flow constraint, an operating voltage horizontal constraint, a branch circuit current limitation, a voltage harmonic distortion rate limitation, a short circuit current limitation and the like as constraint conditions; solution is carried out by an improved Big Bang-BIg Crunch optimal searching method; and the distributed photovoltaic grid-connected acceptable capacity calculating method can provide guidance for planning, building and operation of a photovoltaic access system.