To address the problem of backscattering in underwater optical imaging, a method of push-broom underwater ghost imaging computation is studied. A push-broom computation mode for ghost imaging is introduced. Multiple detection lines are combined to form a joint compressive sensing model by exploiting the inter-line correlation. Iterative shrinkage thresholding method is used to solve the model. An experiment setup of underwater ghost imaging computation is established. The proposed method is experimentally compared with traditional plane-array ghost imaging computation methods under different turbidities. Experimental results show that the proposed scheme can reduce the backscattering effectively.