  The quantum gravity is formulated based on gauge principle. The model
discussed in this paper has local gravitational gauge symmetry and
gravitational field is represented by gauge potential. A preliminary study on
gravitational gauge group is presented. Path integral quantization of the
theory is discussed in the paper. A strict proof on the renormalizability of
the theory is also given. In leading order approximation, the gravitational
gauge field theory gives out classical Newton's theory of gravity. It can also
give out an Einstein-like field equation with cosmological term. The prediction
for cosmological constant given by this model is well consistent with
experimental results. For classical tests, it gives out the same theoretical
predictions as those of general relativity. Combining cosmological principle
with the field equation of gravitational gauge field, we can also set up a
cosmological model which is consistent with recent observations.
