In this paper, a multi-static system working in an active way is made up of ionospheric oblique backscatter sounding system (IOBSS) and two separate receiving stations, which adopts discontinuous wave mechanism. We have advanced a new model that contains skywave condition to locate over-the-horizon targets. We use a single quasi-parabolic (QP) ionosphere model and an analytic ray-tracing program to obtain the coordinate registration (CR) index, which changes skywave group range to ground range. Also, IOBSS and other two receiving stations use this distance information to locate the target which is far away from the system. The analytic expression for the geometric dilution of precision (GDOP) under different station deployments are obtained, which shows GDOP is influenced by the system measurement precision, the stations’ coordinates, and CR index. By computer simulation, we find that GDOP of isosceles right triangle deployment is smaller than that of line deployment and location precision will be improved with increasing base line length. The results indicate that this model is practicable with an acceptable range of error (less than 500 m under certain conditions in this paper). In this paper, a multi-static system working in an active way is made up of ionospheric oblique backscatter sounding system (IOBSS) and two separate receiving stations, which holds discontinuous wave mechanism. We have advanced a new model that contains skywave condition to locate over-the-horizon targets. We use a single quasi-parabolic (QP) ionosphere model and an analytic ray-tracing program to obtain the coordinate registration (CR) index, which changes skywave group range to ground range. Also, IOBSS and other two receiving stations use this distance information to locate the target which is far away from the system. The analytic expression for the geometric dilution of precision (GDOP) under different station deployments are obtained, which shows GDOP is influenced by the system measurement precision, the stations’ coordinates, and CR index. By computer simulation, we find that GDOP of isosceles right triangle deployment is smaller than that of line deployment and location preci sion will be improved with increasing base line length. The results indicate that this model is practicable with an acceptable range of error (less than 500 m under certain conditions in this paper).