The invention discloses boron-containing low-lead composite free-cutting steel which comprises the following components by weight percent: 0.09%-0.18% of C, less than 0.08% of Si, 1.2%-1.5% of Mn, not more than 0.015% of P, not more than 0.015% of S, 0.05-0.07% of N, 0.03-0.05% of B, 0.01%-0.029% of Pb, 0.001%-0.009% of Ca, 0.002%-0.0080% of Mg, 0.01%-0.02% of Al, 0.01%-0.03% of Ni or 0.01%-0.05% of Cu or 0.03%-0.05% of Cr or a mixture of more than two components at any ratio, wherein the content of the mixture is 0.04%-0.06%. The boron-containing low-lead composite free-cutting steel has excellent mechanical property and hot-working property, is suitable for industrial production of continuous casting and continuous rolling, and extremely low in pollution, and can be recycled; and safeguard procedures do not need to be taken by processing and smelting personnel.