The field dependent compact model of backscattering coefficient and quasi-ballistic mobility of charge carriers in graphene have developed for two different substrates: silicon dioxide (SiO 2 ), and hexagonal boron nitride (h-BN). The formulation of the backscattering coefficient is performed using the Landauer and McKelvey Flux Theory (MFT) in quasi-ballistic regime. In graphene, acoustic phonon (AP), surface optical phonon (OP) and charged impurity (CI) scatterings are present among the charge carriers. That is carefully considered during the formulation of backscattering coefficient (R) and quasi-ballistic mobility ( µ eff ) . We find that the Graphene Field Effect Transistor (GFET) with h-BN substrate has the lower backscattering and higher quasi-ballistic mobility. The modeled expression of backscattering coefficient and quasi-ballistic mobility is substituted in drain current ( I DS ) of GFET devices having SiO 2 and h-BN substrate, have shown good agreement with the experimental results.