Abstract:  In this paper we study the site placement problem of distributed MIMO sky-wave over the horizon radar based on Cramer-Rao bound for target localization. Cramer-Rao bound (CRB) for target localization of distributed MIMO sky-wave over the horizon radar is derived according to the geometry of transmitter sites, ionospheric channel, target and receiver^, sites. Let the CRB be the objective function, the sites, number of transmitters and receivers be constraints, optimization equation is established, which is a nonlinear mixed integer programming problem and complicated. Then, using numeric ray tracing, the sites of transmitters and receivers are transformed to the mirror symmetry counterpart respectively, the problem is transformed to a nonlinear 0-1 integer programming. The Binary quantum-behaved particle swarm optimization (BQSPO) algorithm is modified to solve this problem. Lastly, sites placement for different number of sites, different target and channel conditions is simulated, an optimized sites placement is given accordingly. The performance of the modified BQSPO algorithm is also analyzed concisely.