A method for fabricating three-dimensional (3D) photonic crystals (PhCs) easily and simply, by using a visible light (~532 nm) to pass one triangular pyramid to form non-coplanar multi-beam interference, named laser interference etching technique, is reported. In the experiment, we exposed a 9-μm-thick photo-resist on the silicon substrate with exposure intensities of 150, 180, and 220 mJ/cm2, and produced the periodical nanostructures. Through varying a common angle in the triangular pyramid, other interference patterns can be obtained to fabricate various PhCs.