The space-time structure of the superposition of two colinear kerr black holes is studied by the imaginary weyl coordinate method. The space-time region within the horizons in this case is described. Also, the variation of the shape of the inner infinite redshift surface and theposition change of singularities with z0 when 2z0>(M12-a12)1/2+(M22-a22)1/2 is obtained. Fromthis, we can conclude that when z0→(M2-a2)1/2, the space-time structure does not tend to one kerr space-time for parallel identical kerr solutions or one Schwarzschild-NUT metric for anti-parallel identical kerr solutions even though the structure of the space-time outside the outer horizons does, and that there exist the solutions of Einstein's equations without naked singulari-ties (but not without any singularity) when 2z0>(M12-a12)1/2+(M22-a22)1/2.