Abstract: To solve the problem of high sidelobe in nonuniform linear array multiple input multiple output(MIMO) radar, a new method based on array interpolation is proposed to reduce the sidelobe level. First, the nonuniform linear MIMO radar equivalent array formed by matched filter is transformed into uniform linear array, and then the back projection(BP) algorithm is used to achieve high resolution image. Both theoretical analysis and simulation results demonstrate that the proposed method is effective to reduce nonuniform linear array MIMO radar sidelobe level and improve the imaging quality.