The experimental and theoretical investigations of the plasma produced by XeCl excimer laser evaporation of YBa2Cu3O7-aaaaaaaaaaaaaaaaa target are presented in this paper. The plasma emission spectrum was analysed with the Optical Spectrum Analyser (OSA) and a series of species in the plasma plume were resolved. Then the time-of-flight spectra of the species were measured using a monochromator with an optical fibre sampling system. An expansion model of the plasma plume was suggested on the basis of the experiment. By using the model, the time-of-flight spectra, the spatial characteristics of the plsma plume and the distribution of the superconducting thin film thickness deposited by the plasma were simulated. The calculaton results are in good agreement with the deposition experiments.