The invention discloses a multi-cladding optical fibre and a multi-core optical fibre coupler. The multi-core optical fibre coupler comprises N multi-cladding optical fibres and a bushing; the multi-cladding optical fibre comprises a fibre core and multiple claddings encircling the fibre core; the multiple claddings sequentially comprise an inner cladding, a sunken inner cladding, an annular cladding, an outer cladding, a sunken outer cladding and a mechanical cladding from inside to outside; the multi-core optical fibre coupler is obtained by inserting the N multi-cladding optical fibres intothe bushing, tapering and cutting the bushing at one point in the middle of the bushing and welding a multi-core optical fibre; after the N multi-cladding optical fibres are inserted into the bushingand tapered, the fibre core, the inner cladding, the sunken inner cladding and the annular cladding of each multi-cladding optical fibre of the tapered end form a tapered fibre core; and the outer cladding, the sunken outer cladding and the mechanical cladding form a tapered cladding. According to the multi-core optical fibre coupler provided by the invention, after being tapered, the multi-cladding optical fibre can be in low-loss welding with the multi-core optical fibre, and also can be in low-loss welding with a standard single-mode optical fibre; and furthermore, the macrobend loss is relatively low.