The invention relates to a method of using a membrane distributor to greenly prepare cuprous oxide with controllable morphology. The method comprises: using a raw material (mixture of copper salts, alkali sources and citrates) of cuprous oxide as a continuous phase and the reducing agent glucose as a disperse phase, passing the disperse phase through membrane holes at a certain rate into the continuous phase, allowing reacting to form cuprous oxide particles of specific morphology, filtering, washing, and drying to obtain cuprous oxide powder. The method has the advantages that cuprous oxide particles having different morphologies, such as sphere, cuboid, truncated octahedron, octahedron and octangle, and different particle sizes can be prepared just by adjusting reaction material concentration; the reaction solution is quickly and efficiently mixed in micro drop form via a membrane dispersion technique, mass transfer is enhanced, the product has uniform and regular particle size and morphology; using high-price surfactants and toxic reducing agents or organic solvents is not required; the method features good operational convenience, greenness, safety, good amplifying convenienceand the like.