The invention discloses a tank-type breaker and a static-end air retaining device thereof. The static-end air retaining device of the tank-type breaker comprises a static insulated supporter, wherein a static contact base and an air retaining hood are arranged on the static insulated supporter; an exhaust hole is formed in the static contact base; and a pressure relief hole which is communicated with the exhaust hole in the static contact base is formed in the air retaining hood. The pressure relief hole is added to the air retaining hood; and hot airflow sprayed from an opening of the static contact base does not cause deformation of the air retaining hood due to over-high pressure in the air retaining hood, so that the insulating level of the breaker is ensured.