With high diffractive efficiency, Continuous Relief Diffractive Optical Elements (CR-DOE) can be used to eliminate chromatic aberration, partial aberration and simplify optical system. The technology for CR-DOE with Laser Direct Writing method has advantages of simple process, short period and low cost. The paper studied on the characterization method of laser power for the technology. The principle of mask fabrication of CR-DOE by Laser Direct Writing is described in the paper. The relations between microstructure depth and laser power, exposing position radius and laser power were studied. The results showed that microstructure depth changes in direct ratio to laser power and laser power should change in direct to exposing position radius while several same depth microstructures were fabricated at different radius. At the end, the paper gave the charactering method and also fabricated the mask of a kind of centrosymmetric continuous relief diffractive focus lens with the method.