The Helmhotzequation oflightbeam propagating through a mediumof complex refractive indexis reduced totheaxial-coordinate-dependent Schrödingerequation ofcomplexpotential. Thenewbravector,thenewexpectationvalueof a dynamical variableandtheextended Heisenberg picturearedefinedby the inverse oftheevolutionoperator instead ofitsHermitianadjoint, andthecomplexbeam propagation parametersdefinedin terms ofthenewexpectationvalue, the complexABCD law and theABCD formulationof the Huygens’ integralarediscussedin terms of quantummechanics. Itis shown thattheevolutionequationsof the complex beampropagation parameters are the sameas those ofthebeam propagation parametersof beampropagating throughamedium ofreal refractiveindex. The researchon anopticalsystem oftheconservative complexbeam quality factorshowsthat the complexABCD lawholds, the evolution ofitscoordinate operator and the momentumoperator islinear,andtheHuygens’integral isof theABCD formulation.