We adopted Hu Ning's expression of pseudo-energy-momentum tensor density for the gravitational field. From it, we obtained a regular result of the energy of a double-star system. But the distribution of this energy in space cannot be determined uniquely and its distribution laws are essentially identical to those of Schwarzschild external field of an isolated static star. If we recognize that the gravitational field produced by the source matter no longer possesses gravitational mass, then the value of n in that expression can be determined, and the distribution of field energy can also be determined consequently.