A simplified lattice structure for first-order linear-phase filter banks (FOLPFBs) is presented in this paper. A FOLPFB is a generalized version of biorthogonal linear-phase filter banks regarding their synthesis filter lengths. FOLPFBs' structure is more complicated and has more parameters than that in other FBs. We propose a method to reduce their redundant parameters without losing their properties. Moreover, regularity can be imposed which reduces the design freedom as well as improves the perceptual quality in image coding.