The invention discloses a secondary reinforcement method for shield tunneling crossing of a water-rich sand layer near a river. The method mainly comprises the following steps of (1) previous preparation; (2) installation of a drilling device; (3) drilling; (4) installation of freezing pipes. According to the method, tube curtain freezing is formed through the freezing pipes, and liquid ammonia isintroduced into the freezing pipes to freeze water in the water-rich sand layer, so that an anti-seepage effect in a shield tunneling process is improved, and shield tunneling excavation is facilitated. Inner-layer fixing piles and outer-layer fixing piles are internally filled with heat insulation plates, the heat insulation plates achieve a heat insulation effect, and the frozen soil curtain performance including the range and strength declines by reducing an external heat source. Concrete is poured into the fixing piles, the structural strength of pipe curtains of pipe curtain grouting pipes is improved, the quick ablation effect of flowing water on frozen soil is reduced, and the problem is solved that when existing freezing methods are adopted for freezing soil layers in the shield tunneling process, the operation is likely to be affected by external temperature and thus the anti-seepage effect of the freezing methods is affected.