Taking 3 kg 2, 4, 6-trinitrotoluene (TNT) explosive exploding in the explosion water-well with steel-linner with internal diameter and depth both of 11 m as the research object, based on numerical simulation, several concerned dynamics problems in the design of explosion well, such as the influence of thickness of the steel-inner and concrete cofferdam thickness to the force and deformation of the steel, setting the bubble curtain in the well to improve the facilities security and so on, are studied. The results show that the underwater explosion shock wave parameters in the well are consistent with the result of the calculation by P. Cole formula. The biggest force and deformation of the inner wall of the steel-inner appears below the horizontal line of the center of the charge, when the thickness of steel-inner reaches 50 mm. The equivalent plastic strain where is 1.6 m far away from the bottom of steel-inner can attain 0.16 %, but this does not meet the conditions of the strength theory. When the thickness of steel lining is 20 mm, plussing 0.5 m thick concrete cofferdam,the explosion well with steel-inner meets the requirements of safety design. Setting a bubble curtain, the radius of which is 4.9 m and the thickness is 0.05 m, can make the peak pressure of the shock wave near the steel wall be decreased by 40.6 %. When the thickness of the steel-inner is 20 mm and the thickness of concrete cofferdam is over 0.35 m, it will be able to meet the requirements of the security design by taking the bubble curtain method to attenuate the shock wave. The conclusions above can offer the method and the basis for the structural design of the explosion well with steel-inner and safety assessment.