This paper is concerned with the following quasilinear Schrödinger equations:{−△u+V(x)u−△(u2)u=λup−1uinRN,u>0,u∈H1(RN), where λ>0, 1<p<22⁎−1, 2⁎=2NN−2 and N≥3. Under some suitable assumptions on V(x), we prove the existence of ground state solutions via Pohožaev manifold method. The novelty of this works with respect to some recent results is that we treat the existence by using Pohožaev manifold method in an Orlicz space and this enables us to handle the nonlinearity in a uniform way. As its supplementary results, we also prove the nonexistence of least energy solutions for 1<p<22⁎−1.