Abstract: In light of the fact that enormous elements exist when applying the uniform rectangular planar array to skywave Over-The-Horizon Radar (OTHR), the sparse optimization approach of the uniform 2-D arrays using an improved genetic algorithm is proposed as follows: an optimal model for the sparse rectangular planar array is established from the view of beam shaping; initial population of the genetic algorithm is identified by elevation beam on the bases of the Direction-Of-Arrival (DOA) of multi-mode propagation echoes; the fitness function is revised for the purpose of avoiding early maturing and random walk; and both crossover and mutation operators are improved in order to achieve precise control of the sparsity ratio. Simulation results indicate that the precise control of the sparsity ratio and the optimized performance are obtained by using the improved genetic algorithm. Finally, the paper analyses the feasibility of 2-D arrays application into the OTHR engineering, indicates the conditions for application and existing technical challenges, and then presents the solutions accordingly.