The invention is suitable for the field of laser processing, and provides a green light laser zooming and beam expanding system comprising a first lens, a second lens and a third lens. The first lens and the third lens present to be plane-convex positive lenses. The second lens presents to be a convex-concave negative lens. The first lens, the second lens and the third lens respectively comprise a first curved surface and a second curved surface, a third curved surface and a fourth curved surface, and a fifth curved surface and a sixth curved surface. Curvature radiuses of the first to the sixth curved surfaces are indefinite, -29.8, 7.2, 1.6, indefinite and -100. Center thicknesses of the first to the third lenses are 2, 1 and 4. External diameters of the first to the third lenses are 10, 3 and 34. Ratios of refractive indexes to abbe numbers of the first to the third lenses are 1.8:25, 1.48:68 and 1.8:25. Spacing distance between the second curved surface and the third curved surface is from 8 to 28mm, spacing distance between the fourth curved surface and the fifth curved surface is from 107 to 115mm, and tolerance is 5%. Beams of incident light can be expanded for 2 to 16 times by the system so that the system is applicable to lasers with different emergent diameters and divergence angles, and efficiency and accuracy of laser processing are enhanced.