The invention discloses pineapple fiber pulp and a preparation method thereof. Pineapple fibers are taken as raw materials of the pineapple fiber pulp. The preparation method comprises the following steps: preprocessing, integrating stewing and bleaching, washing by a vacuum washer continuously beating, carrying out pressure sieving twice, carrying out acid treatment, washing by water, and pulping to obtain the pineapple fiber pulp. According to the preparation method, the pineapple fiber pulp is prepared from the pineapple fibers; the stewing and bleaching processes are integrated, so that the operation is simple and convenient, the production cycle is remarkably shortened while the stewing and bleaching quality is guaranteed, the production process is simple, the flow process is short, the energy consumption is low, indexes such as CODcr (chemical oxygen demand) in a stewed black solution are remarkably lowered in comparison with those in a conventional process, and the wastewater treatment cost is reduced; prepared regenerated cellulose viscose fibers have excellent performance of general viscose fibers, fabrics of the regenerated cellulose viscose fibers remain the bacterial resisting and inhibiting performance of raw hemp, and thus the commercial exploitation value of the pineapple fibers is improved.