Abstract: The paper reports the formation and regeneration of protoplast from the new antibiotics, Micromonospora M-90, as well as the effects on antibiotics yield producing strain. Under the conditions of 35℃ and 2 mg/ml of lysozyme, the secondary mycelia of M-90 was cultured and enzymelysed, and was protoplast formed at 10/ml; the regeneration rate reached to 20% under the selected regenera-ting conditions; the antibiotics yield of the regenerated protoplast colony was increased by 34% as compared with the control.