The radiative decay Bs->phi gamma is one of the benchmark channels in the physics programme of the LHCb experiment. It allows us to test the Standard Model through the indirect measurement of the photon polarization in Bs->phi gamma transitions. The estimation of the statistical error of the CP-violation parameters obtained with Monte Carlo simulation is presented. It is shown that the expected statistical uncertainty in the wrong photon polarization fraction is ~0.2 with the 2 fb^{-1} of integrated luminosity.