This article has as a starting point the definition of the concept of ecological principles. Then, after classification of the principles of ecology (domestic principles and international principles), we present and critically analyze and compare the main principles in the field of ecology. Among the ecological principles on the domestic chain, we present and analyze 11 principles, namely: pollution must be combated at the source; the interests of environmental protection must be taken into account in all design or execution decisions; any exploitation or use of natural resources must be avoided if it is accompanied by damage; it is necessary to raise the level of scientific and technological knowledge, inter alia by supporting scientific research; the costs of preventing and combating pollution to be borne by the polluter; the activity of one state not to harm the environment of another state; during the elaboration of the community policy in the field of environmental protection to take into account the interests of the developing states; community environmental protection policy must be developed in the long term and protection must be comprehensive and international, which is achieved, inter alia, through cooperation within international bodies; the cause of environmental protection is everyone's responsibility and for this reason education is irreplaceable; depending on the source of pollution, the most appropriate level of action must be established taking into account the nature of the pollution, the necessary measures, the characteristics of the protected territory. This principle is defined as a "subsidiary principle"; it is necessary to harmonize and coordinate national policy in the field of environmental protection in accordance with the long-term commonly accepted directives. We also present and analyze the principle according to which environmental protection must be an essential element of the economic and social policy of the state. Finally, another ecological principle, the principle of prevention of ecological risks and damage