Some quantum walks can be modeled using weighted graphs, where each vertex represents a qubit, each weighted edge indicates the coupling strength between two qubits, and each weighted loop indicates the strength of the magnetic field of a qubit. In this talk, I will discuss two analytic approaches to quantum walks: orthogonal polynomials, which have been applied mostly to weighted paths, and spectral graphs theory, which has been applied mostly to simple unweighted graphs. I will also talk about some interesting relations between quantum walks on weights paths and quantum walks on simple unweighted graphs.