The invention relates to a construction technology for positioning tunnel second lining steel bars, mainly aiming at solving the problems that the precision of a layer distance between inner and outerlayers of the steel bars and the distance between the steel bars is low and the like, caused by the fact that second lining steel bars are manually positioned at present. Layer distance positioning angle iron is arranged between inner and outer layers of annular steel bars of the second lining steel bars, and annular steel bar limiting grooves are formed in two pieces of channel steel; the channel steel for limiting the inner and outer layers of annular steel bars is arranged at the top of the layer distance positioning angle iron; each annular steel bar limiting groove stretches out from thelayer distance positioning angle iron; the two pieces of channel steel are fixed with the layer distance positioning angle iron through bolts; the inner and outer layers of annular steel bars are clamped in the annular steel bar limiting grooves of the channel steel for limiting the inner and outer layers of annular steel bars, and all the inner and outer layers of annular steel bars are clung tothe layer distance positioning angle iron; the steel bars are bound and concrete is poured. The construction technology has the advantage that the layer distance and distance precision of the inner and outer layers of annular steel bars can be ensured.