The integration of distribution generation with high penetration is the future development trend of distribution network, the certainty load flow calculation cannot deal with the volatility and randomness on the power flow in distribution network that is brought by distributed generation. To solve this problem, this paper builds up the probability model of distributed generation based on the theories of probability and statistics. In the basis of forward-backward sweep method and by considering the influences posed by the fluctuation of distributed generation and electrical load on the load flow calculation, the probabilistic power flow calculation of distribution network with distributed generations based on the two point estimation method is propoed. The simulation result of the implementation of this method on an IEEE 33-bus test system show that the two point estimation method can achieve the same precision as that of the Monte Carlo method while has the advantage of fast resolving speed.