A microscopic cluster model with a fully correlated Gaussian basis is developed. In the model, the stochastic variational method is used in order to calculate the ground-energy and the mean-square radius conveniently. Based on this model, the ground-energy level and radius of the neutron halo nucleus, ^6He, are calculated as a α＋n＋n three-cluster model. The results are in good agreement with the experimental data.
