The invention relates to a weight-losing konjac gulcomannan meal nutritional bar and a preparation method thereof. The preparation method of the weight-losing konjac gulcomannan meal nutritional bar comprises the following steps: weighing of raw materials, preparation of a mixed solution, mixing of the raw materials, material discharging and forming. By the use of the health effect of natural macro-molecular polysaccharide of konjac gulcomannan and the characteristics of satiety and no heat, the konjac gulcomannan is prepared into a meal nutritional bar for diabetes patients and weight-losing people. Furthermore, by the adding of sugar alcohol, proper sweetness can be provided for the product, and blood sugar fluctuation cannot be caused after people eat the bar; by the adding of whole egg powder, apricot kernel powder, fruits and enough grains, the product is enriched by nutrition. The weight-losing konjac gulcomannan meal nutritional bar is low in cost, small in size, low in heat and balanced in nutrition, tastes good, can replace lunch and dinner and achieve an effect of reducing fat, and can meet the demand of a human body for nutrition.