Reverse osmosis membrane assembly manufacturing method, reverse osmosis membrane element and water purifier

The invention provides a reverse osmosis membrane assembly manufacturing method, a reverse osmosis membrane element and a water purifier, and the reverse osmosis membrane assembly manufacturing method comprises the following steps: folding the front side of a first reverse osmosis membrane, and dividing the folded first reverse osmosis membrane into a first membrane and a second membrane by taking a folding edge as a boundary; a first raw water flow channel is formed between the front surface of the first membrane and the front surface of the second membrane, and a first reverse osmosis membrane element is rolled; the front face of the second reverse osmosis membrane is folded, the folded second reverse osmosis membrane is divided into a third membrane and a fourth membrane with the folded edge as the boundary, a second raw water flow channel is formed between the front face of the third membrane and the front face of the fourth membrane, the circulation sectional area of the first raw water flow channel is S