The invention relates to a method for management of muddy coastal mudflat by echelon plantation of suaeda salsa, alfalfa and maize. The method includes: establishing a level-2 water draining and salt leaching system in a muddy coastal mudflat region; establishing a salt leaching and soil fertility improving plow layer; establishing a rainwater and freshwater resource utilization combined echelon propelled biological improvement mode. According to a plant-soil adaptability principle, echelon plantation of suaeda salsa, alfalfa and maize is carried out to realize echelon degradation of coastal saline soil from coastal saline soil, severe salinized soil, moderate salinized soil to plow land, wherein the suaeda salsa is a pioneer halophilous plant, the alfalfa is a salt-tolerant soil improving plant, and the maize is a field crop. Problems of high cost of physical and chemical measures for management of saline-alkali soil and long time of biological measures are solved, organic combination of ecological restoration and agricultural production is realized, a win-win purpose of ecological benefits and economical benefits is achieved, and technical supports are provided for utilization of coastal mudflat farmland.