Current-voltage characteristics for superconducting tin films, which are long (about 100 mum), wide (up to 50 mum) and thin (about 100 nm), that satisfied the conditions of type 11 superconductor, were investigated experimentally under the electromagnetic irradiation of frequency from 10 MHz up to 15 GHz. The formation of phase-slip line (PSL) at the background of vortex dynamics was studied. Despite the existing of vortices, the process of PSL formation at current values that exceed a critical one is the same as the phase-slip center (PSC) formation in the vortex-free superconductors. It means that PSL is a line across the sample, at which order parameter oscillates with Josephson frequency becoming zero at some moments of time. The formation of high frequency PSL was observed under the influence of external irradiation. The enhancement of superconductivity was discovered and analyzed what was measured earlier only in vortex-free superconductors.