  We discuss the scattering of a quantum particle by two independent successive
point interactions in one dimension. The parameter space for two point
interactions is given by $U(2)\times U(2)$, which is described by eight real
parameters. We perform an analysis of perfect resonant transmission on the
whole parameter space. By investigating the effects of the two point
interactions on the scattering matrix of plane wave, we find the condition
under which perfect resonant transmission occurs. We also provide the physical
interpretation of the resonance condition.
