Cotton rope has good water transport performance and plasticity. An efficient three-dimensional evaporator for solar evaporation was prepared by winding the cotton rope into different shapes and covering its surface with carbon black (CB). The light absorption of the evaporator coated with CB was significantly improved, and the average absorptance was 95.8% over the solar spectrum. Using a one-dimensional channel for water supply, the evaporator and bulk water were separated, and thermal localization was realized without thermal insulation materials. The influence of the evaporator shape on evaporation performance was analyzed. Under the same conditions, the evaporation rate of funnel-shaped evaporator was the highest, reaching 1.3033 kg / m² h. The multiple reflection of light in the funnel-shaped evaporator promoted the capture and absorption of incident light. For the evaporator with a reflector placed below, the evaporation rates of funnel-shaped, plane-shaped, and umbrella-shaped evaporators increased by 2.3%, 1.67%, and 0.814%, respectively. In addition, the evaporator has a self-cleaning function. The salt deposited on the surface can be redissolved and leaves the evaporator with water. An efficient solar evaporator was designed in a simple and economical way. Its self-cleaning function is especially suitable for seawater desalination.