In order to realize sparse arraying of MIMO radars, this paper presents an optimized design method for MIMO radar array pattern based on Ant Lion Optimizer (ALO).First, the aperture of the transmitting elements and the receiving elements as well as the minimum distance between them are defined.Then, the ant lion algorithm is used to optimize the position of the elements, the fitness function is calculated and compared with the global optimal solution to obtain and save the optimal value, so as to minimize the peak sidelobe level.The number of effective elements and peak sidelobe are taken as multi-objective optimization functions, which are then transformed into single objective optimization by normalization.The results of simulation show that, compared with the existing algorithms, the proposed algorithm has better sidelobe optimization effects and is not prone to fall into precocity.It can also realize multi-objective joint optimization and improve the performance and degree-of-freedom of the radar.