The invention provides a preparation method of a continuous basalt fiber. The continuous basalt fiber is prepared from the following raw materials including coal ash and gangue. With the adoption of the preparation method, the continuous basalt fiber is prepared with industry waste solid with the chemical components similar to those of basalt as a main raw material and iron tailings, titanium containing slag, alumina red mud and the like as additives, the components are reasonably proportioned and exert synergistic effect, and silicon dioxide and aluminium oxide as main components in the waste solid, iron oxide contained in the iron tailings, titanium oxide contained in the titanium containing slag and aluminium oxide contained in the alumina red mud are fully utilized, so that the continuous basalt fiber which is prepared by coupling the components has performance excellent superior to that of the traditional continuous basalt fiber, and the efficient utilization of the waste solid is effectively realized.