The invention belongs to the field of crops fertilizers and in particular relates to an ecological potassium fertilizer and a preparation method of the ecological potassium fertilizer. The ecological potassium fertilizer is mainly prepared from potassium sulfate, pine bark, humic acid, urea and natural minerals. The pine bark is treated firstly to remove substances harm to the crops, and then the treated pine bark is mixed with potassium sulfate, humic acid, urea and natural minerals to obtain the ecological potassium fertilizer. The ecological potassium fertilizer mainly adopts natural organic matters and is environment-friendly, the quick-acting fertilizer can be provided for promoting the rapid growth of the crops, and the loss of a great amount of potassic fertilizer in soil can be avoided; and besides, the soil is improved, the soil caking phenomenon is improved, the organic matters in the soil are increased, the microorganism activity is improved, the stress-resistant and disease-resistant capability of the crops is improved, the successive cropping obstacle can be relieved after the fertilizer is applied year by year, the quality of agricultural products is improved, the environment pollution is reduced, and the ecological potassium fertilizer is safe and non-toxic to human, livestock and environment and is environment-friendly.