The invention discloses a manufacturing method of a flexible building wall. The method is characterized in that a three-layer structure, including a nano fiber layer at the inner layer, a flexible vibration absorbing and damping layer at the middle layer, and a glass fiber mortar layer at the outer layer, are sequentially combined to manufacture the flexible building wall; the organic combination of the three layers of composite materials enable the density reduction on the premise that the voice insulation and the temperature insulation functions of the wall are ensured, and the mass of the whole wall is reduced. The flexible building wall is flexibly applied to a modular middle area of a building, and is high in voice insulation performance; in addition, the wall is thinner than a common solid wall, so that a certain use area is increased, and the building area is reduced; the surface of a wallboard is high in decoration performance and flatness, so that the later decorating and the coating decorating are easier than those of a traditional wall; cracks are hardly caused; the voice insulation effect is outstanding.