The invention relates to an optical cable of central beam tube type, comprising a core and an outer guard layer covering the core, wherein the core comprises a loose tube and a plurality of colored optical fibers or tight buffered optical fibers which are provided in the loose tube and axially extended along the loose tube, a waterproof yarn is provided in the loose tube and axially extended along the loose tube. The invention uses the waterproof yarn to replace traditional fiber paste to provide uniform protection for water transfer, make optical fibers attain high sensing sensitivity and make the optical cable attain good beading property, therefore, the optical cable of central beam tube type has wide application.