On this basis of the analysis on the control principle of roadway section forming in tunneling by boom-type roadheader,a geometric parameter matching model of roadway section based on angular displacement and the displacement of detecting cylinder was established,the mathematic relationships between the dimension of roadway section forming and the detection volume of sensor and between the control accuracy of roadway section forming and the precision of sensor were arrived.These provided a theoretical basis for the accuracy choice of senor for the forming control of roadway section and the collect of the visualization data for the track monitoring system of cutter.