The invention relates to a method for constructing a deep pool and a shoal in a straight river channel. In the method, a spur dike is arranged on the left bank side of the straight river channel, a bank slope on the opposite bank of the spur dike is protected by riprap, a diving guide wall is arranged on the left and right banks of the downstream side of the spur dike respectively, the discharge cross section of the river channel is shortened by the spur dike to increase the flow rate of water flow, the bottom of a river bed of a river reach between the diving guide walls on the downstream side of the spur dike is continuously scoured to naturally form the deep pool, and a dead water area or slow flow water area formed between the diving guide wall and the river bank becomes the shoal through long-term deposition. The method has the advantages that: the deep pool is naturally formed and becomes a rest place for aquatic organisms such as fishes and the like, and can become a shelter for the aquatic organisms such as the fishes and the like in a flood period; plants can be planted on the shoal, and the shoal can become an organism habitat different from the deep pool; and the complexity of a river channel structure and water conservation condition diversity can be increased or repaired, and river biodiversity, population composition and rare species conservation are facilitated.