Many quasi-one-dimensional (Q1D) organic crystals, known as synthetic metals at room temperature, become insulators when the temperature decreases, due to a Peierls transition. In the crystals with half-filled Brillouin zone, the dimerization of lattice takes place at some critical temperature that determines the phase transition. In this paper, the Peierls structural transition in Q1D organic crystals of TTF-TCNQ is studied in 3D approximation. In the physical model of the crystal, it was simultaneously taken into account two the most important interactions of conduction electrons with the longitudinal acoustic phonons. One of them is of the deformation potential type and the other interaction is similar to that of a polaron. The ratios of amplitudes of the second interaction to the first one are characterized by the parameters γ1, γ2 and γ3, respectively. The equation for phonon Green function is deduced in the random phase approximation as a sum of diagrammatic ladder series of close loops of electronic Green functions. The polarization operator as a function of threedimensional phonon wave vector q is calculated for different values of temperature. In result, the Peierls critical temperature is determined.