Interfacial stress distribution of bonded quarter-planes subjected to a concentrated force was re-investigated based on Bogy’s solution. The characteristic length of the singular interface end, δ, was defined, and found varying in a very large size scale with the index of stress singularity from millimeter to nanometer or even smaller scale. The influences the characteristic length scale on the initial debonding of the interface end is a new question worth to pay attention. Photoelasticity experiment was employed to verify whether the initial debonding is always located at interface end with stress singularity. The test results show that the initial debonding does not start from singular interface end if the index of stress singularity is small enough.