钢芯铝缆，或称钢芯铝线(Aluminium Conductor Steel Reinforced, or ACSR)，是使用在架空电在线，以拉力强之钢线作为导线之心，周围绕以铝线供通电的缆线。外层使用铝线因铝具有良好导电性、重量轻、较铜便宜。内层使用钢线因其拉力强。侥幸的是，虽然钢线的导电性较差，但由于集肤效应，电流大部份经由缆线外层通过。因此内层导电性较差也无所谓，内层阻抗越高越好。

Aluminium conductor steel-reinforced cable (ACSR) is a type of high-capacity, high-strength stranded conductor typically used in overhead power lines. The outer strands are high-purity aluminium, chosen for its excellent conductivity, low weight and low cost. The center strand, or strands is/are of steel for additional strength to help support the weight of the conductor. Steel is higher strength than aluminium which allows for increased mechanical tension to be applied on the conductor. Steel also has lower elastic and inelastic deformation (permanent elongation) due to mechanical loading (e.g. wind and ice) as well as a lower coefficient of thermal expansion under current loading. These properties allow ACSR to sag significantly less than all-aluminium conductors. Per the International Electrotechnical Commission (IEC) and The CSA Group (formerly the Canadian Standards Association or CSA) naming convention, ACSR is designated A1/S1A.