The invention discloses an optical-fiber adjustable filter. The filter comprises an optical fiber, a ceramic insertion core, self-focusing lenses, a Filter optical filter, an external optical coating film layer, a collimating connection sleeve and PIN joints. The optical fiber penetrates a center of the ceramic insertion core. Two ends of a filter are provided with the self-focusing lenses respectively so as to realize focusing and coupling of an optical signal. A cross section of the ceramic insertion core is installed with the Filter optical filter. Grinding and polishing are performed on the ceramic insertion core and an optical-fiber end surface. The external optical coating film layer is adsorbed on the ceramic insertion core and the optical-fiber end surface through an optical coating film. The collimating connection sleeve sleeves the ceramic insertion core. The PIN joints are installed on two sides of the filter. The filter is simple to manufacture, has low cost and possesses reliable quality. Engineering personnel installation operation is convenient, and batch production and a low cost product demand of a client are satisfied.