We present a lattice QCD calculation of the heavy quark expansion parameters mu(pi)(2) and mu(G)(2) for heavy-light mesons and heavy-light-light baryons. The calculation is carried out on a 20(3)x48 lattice at beta=6.0 in the quenched approximation, using the lattice NRQCD action for heavy quarks. We obtain the parameters mu(pi)(2) and mu(G)(2) in two different methods: a direct calculation of the matrix elements and an indirect calculation through the mass spectrum, and confirm that both the methods give consistent results. We also discuss an application to the lifetime ratios.