This paper presents a single-station, multipoint and time-shared position and attitude measurement method of roadheader based on iGPS, which can accurately and unmannedly measure the angle of deviation and offset distance of roadheader. The position coordinates of the receivers fixed at different locations on roadheader body are measured by the single-station, multipoint and time-shared position and attitude measurement system based on iGPS, and the angle of deviation and offset distance of roadheader are calculated through the receiver position coordinates. The mathematical model between the angle of deviation and offset distance of roadheader and the position coordinates of the receivers and measurement parameters is established, and the error transfer equation of angle of deviation and offset distance of roadheader are deduced by the mathematical model and random error modeling theory. The regularity of measurement error of angle of deviation and offset distance of roadheader is studied in different the spacing between the laser stations and the measuring distance between the laser station and the roadheader according to the error transfer equation of angle of deviation and offset distance of roadheader. In order to proof the accuracy and reliability of the method to study the regularity of measurement error of angle of deviation and offset distance of roadheader, a set of high-precision total station experimental system is designed. The experimental results show that the regularity of measurement error of angle of deviation and offset distance of roadheader are basically the same in theoretical simulation and experimental study respectively. To meet the requirements of the use of coal mine roadway, although slightly biased in value. This technology can be applied to the assembly process of large aerospace equipment, and has great application value and theoretical value..