The invention relates to a method of dissolving and processing a bamboo-hemp fibre by adopting an ionic liquid. The method has the following steps: firstly, the comminuted pulp of bamboo and hemp is well mixed with an ironic liquid, dissolved at a temperature of 35 to 160 DEG C, deaerated for 1 to 120 hours, and a homogeneous and stable spinning solution with a total solid content of 3 to 50 percent is formed, wherein, the mass ratio of bamboo and hemp is 1-99 percent to 99-1 percent; secondly, the spinning solution is filtered, deaerated, spinned and solidified through a coagulation bath; and thirdly, a bamboo-hemp blended composite fibre is obtained after the procedures of stretching, water cleaning, bleaching, oiling and drying. The ironic liquid used in the invention has high production efficiency, is easy for callback and conforms to the requirement of a green production. The prepared composite fibre has excellent mechanical strength and mechanical property and the fabric made of the composite fibre has the advantages of excellent hygroscopic property, strong ventilation property, soft handfeel, excellent fabric drapability, easy variegation and powerful bacterium resistance. Simultaneously, the prepared composite fibre provides a material used in the departments of medicine and health.