The effect of the explosive charge with variable clearance and the charge filled with oxidant gel solution into its clearance on detonation performacnce is studied by using ionization method. Experimental results show that steady detonation of the explosive charges with axial clearance of 2 mm is not affected evidently，and detonation velocity of the charges reduce after being filled with the gel solution; however, steady detonation is affected greatly by charge segments and radial clearance size, and detonation performance is improved after being filled with the gel solution.