The 8 connection galleries of Yangtze Rivercrossing tunnel in Shanghai are constructed by freezing method. In the paper, analysis is made on the development rules of the thickness of frozen soil curtain, the average temperature of frozen soil and the temperature of excavation face, on basis of the results of monitoring made during freezing of No. 1 connection gallery. The disadvantages of the original freezing program are discussed and optimized freezing program is proposed. Numerical simulation is made on the development of the temperature field of the optimized freezing program. The freezing effect of the optimized freezing program is analyzed. The practice shows that the optimized freezing program has advantages such as large effective thickness of frozen soil curtain, low average temperature and high freezing efficiency. The study guarantees safe and economic freezing of the other 7 connection galleries.