The invention relates to a manufacturing method of plant fibre products, which comprises the steps: pulverized substances containing textile plants are poured into a banburying kneader and chemical pretreatment solution is added, so the fibre pretreatment chemical modification is realized simultaneously when mechanical physics modifying is realized; after entering into an expansion extruder for expansion modification, the pulverized substances are added with various additives and fillings, which are banburied and kneaded together, and the banburying kneading substance is rolled into particles by a particle rolling machine; or plant fibre subjected to banburying kneading chemical modification and various additives and fillings are directly and together banburied and kneaded and then are extruded and produced to form particles or extrusion sectional materials by the expansion extruder; the produced particles or sectional materials can be used for producing plant fibre products of various types and performances and plant fibre products of sheets, sectional materials, paper, membranes, and the like by utilizing the prior plastic injection machine, extruder, blow moulding machine, rubber refining machine, calander, hot press, and equipment and technology principles of microwave and infrared, steam drying, and the like so as to replace plastic, plastic foam, woodworks, paper and membranes.