In order to measure the distance between the specific point and the artillery slewing axis, the series of measurement methods based on trilateration network were proposed. On the basis of measuring the parameters of the artillery slewing circle of the trilateration network method, these methods project the specific points measured on the gun onto the horizontal plane of the trilateration network. By measuring the distance parameters between the projection points of the specific point on the horizontal plane and more than two projection points on the rotation circle, the relative coordinates of the projection points of the specific point can be calculated, so as to calculate the horizontal distance between the specific point and the artillery slewing axis. According to the redundancy of distance parameters, these methods were divided into non-redundant method and redundant method. The non-redundant method uses the distance intersection solution to calculate the relative coordinates of the projection points of the specific point. For the redundancy method, firstly, all measured parameter values were adjusted by the method of conditional adjustment of trilateration network, and the adjustment values of each measured parameter were obtained. Secondly, the relative coordinates of each point were calculated by the adjustment difference of side length, and the relative coordinates of artillery slewing center were obtained by circle fitting. Finally, the distance between the projection point of the specific point on the horizontal plane and the artillery slewing center was calculated. The simulation results come from Monte Carlo method show that: when testing the measurement conditions that can be realized on site, the measurement errors obtained by several methods are less than 2 mm; with the change of measurement conditions, the measurement error of redundant method is always smaller than that of non-redundant method. The simulation results show the feasibility of the new methods and provide the basis for the revision of national military standards.