A new connecting way wasdone in Yb3+-doped fiber laser, in which a Yb3+-doped fiber waslocated at an unpumped place. Narrow-linewidth lasing was obtained by using of a bandpassfilter and the unpumped Yb3+-doped fiber acted as saturable absorber. Thelinewidth of output laser was less than 0.07 nm. The effect of unpumped dopant fibersaturable absorber in Yb3+-doped narrow-linewidth fiber laser was researched indetail.