The article describes the theoretical foundations of the “linear” method of determining radius of the circular shape structures. The method involves the measurement using a laser rangefinder only two distances: directly from the structures to the rangefinder and to the point of tangency of a line drawn from a point to the location of the rangefinder to a line, forming a structure. Displaying solution of the problem, describes the methodology and results of the modeling, deriving a formula estimating the accuracy of the proposed method. It was found that, since the distance from the rangefinder to the construction that exceeds the radius 3–4 times, error of determination the radius, which depends on the precision of used rangefinder, remains virtually unchanged. We give a diagram of a device for determining on a generator of the structure point of contact. Was made its operating model on the basis of a camera tripod. The article describes the methodology and results of tests conducted on chimney with the radius of the cross section at the bottom of approximately two meters. Mean square error of an individual measurement and probable value made accordingly 9 mm and 5 mm. In order to improve the accuracy of measurements developed ways to improve the construction of the device and improving the methods of its use.