The invention relates to a steel tooth bit used for the drilling fields of petroleum and geology and the like, comprising a bit leg and a steel-tooth cone. The bit leg is connected with the steel-tooth cone through a shaft journal at the lower end of the bit leg; the periphery of the steel-tooth cone is distributed with teeth which are integrated with the steel-tooth cone; and the difference liesin that when the teeth face the drilling of the steel-tooth cone, the autorotation direction is inclined so as to lead the sections of the teeth to form an inequilateral trapezoid. The invention has the beneficial effects that: 1. the stress of the roots of the teeth can be changed by the change of the section of the steel-tooth cone under the condition that a tooth profile angle Beta is constant, thus improving the strength of the teeth of the steel-tooth cone and reinforcing the capability of break resistance; and 2. as the tooth angle of the front of the teeth of the steel-tooth cone is changed to be small, the sharpness and the capability of drilling into the ground are improved so as to lead the cutting property of the drilling of the cone to be further strengthened and lead the conebit to be capable of bearing higher drilling pressure and rotation speed, thus improving the rock-breaking efficiency of the bit of the steel-tooth cone.