In this work we use the equation of state (EOS) of (2+1)-flavor Nambu-Jona-Lasinio (NJL) model to study the structure of the strange quark star. With a new free parameter α, the Lagrangian is constructed by two parts, the original NJL Lagrangian and the Fierz transformation of it, asTo determine the range of α, we compare the binding energies in the 2-flavor and (2+1)-flavor cases. We also consider the constraints of chemical equilibrium and electric charge neutrality in the strange quark star and choose six representative EOSs with different α and B (bag constant) to study their influence on the structure of the strange quark star. As a result, we find that a smaller α or B corresponds to a heavier star with a stiffer EOS. Furthermore, the heaviest strange quark star is in agreement with both the recent mass observation of PSR J0740+6620 and the constraint on tidal deformability of GW170817.

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