The invention belongs to the technical field of semiconductor optic electronics and particularly discloses an aluminum-free semiconductor laser structure. The aluminum-free semiconductor laser structure comprises a buffer layer, a lower matching layer, a lower limit layer, a lower transition layer, a lower waveguide layer, a multiple-quantum-well layer, an upper waveguide layer, an upper transition layer, an upper limit layer, an upper matching layer and an electrode contact layer, which epitaxially grow on a substrate from bottom to top by means of an organometallic chemical vapor deposition method. On the basis of asymmetric waveguide layers, how materials of the waveguide layers and the limit layers of a device influences mode limit factors, absorption loss, threshold current, output power, long service life and reliability is improved, so that a semiconductor layer of new structural system is obtained. The upper limit layer and the lower limit layer are made of InGap materials with small conduction-band difference, the upper waveguide layer and the lower waveguide layer are made of InGaAsP materials with small conduction-band difference and are of aluminum-free asymmetric straight waveguide structure.