As‐deposited epitaxial YBa2Cu3Oxthin films have been prepared by ArF excimer laser deposition followed by a rapid cooling with controlled oxygen pressure. The best film after the rapid cooling has aTcwith a zero resistance of 88 K and aJc(77 K) of 5.5×105A/cm2. It has been observed that thec‐lattice parameter decreases, that is, the oxygen contentxincreases from ∼6 to 7, with increasing oxygen pressure during the rapid cooling. The relation betweenxand oxygen pressure is almost consistent with that for a powder sample being in a thermal equilibrium. We conclude that the oxygen content in the as‐deposited films is determined by the thermal equilibrium oxygen content during the cooling process.