A coverage-type deep-sea mud volcano-associated natural gas hydrate exploitation system, comprising an engineering ship support unit, a power supply unit, a drilling and casing unit and a gas isolation and heat insulation unit, wherein the engineering ship support unit provides basic hardware support for hydrate exploitation and realizes a collection of natural gas hydrates, characterized in that the power supply unit is connected to the gas isolation and heat insulation unit through a power supply cable; the drilling and casing unit comprises a production well, perforated holes and a natural gas transport pipe, wherein the perforated holes are formed in a hydrate enrichment layer in the production well, the natural gas transport pipe has an end disposed in the production well and an end connected to the engineering ship support unit, and a depressurization control valve is disposed on the natural gas transport pipe; the gas isolation and heat insulation unit is regularly laid on a mud volcano, covers the mud volcano and comprises a gas isolation and heat insulation cover connected to the power supply unit, wherein the gas isolation and heat insulation cover sequentially comprises, from bottom to top, a heat-conducting aluminum foil layer, a carbon fiber heating wire layer, an asbestos heat insulation layer and a heat-proof gas isolation layer and supplies heat into a sediment layer to heat a natural gas hydrate reservoir; the gas isolation and heat insulation unit further comprises thermal electrodes which are disposed at positions with a high hydrate saturability and a large thickness, the thermal electrodes and the carbon fiber heating wire layer adopt two independent power supply circuits, and the power supply circuit of the thermal electrodes is separately buried between the asbestos heat insulation layer and the heat-proof gas isolation layer. characterized in that the power supply unit is connected to the gas isolation and heat insulation unit through a power supply cable; the drilling and casing unit comprises a production well, perforated holes and a natural gas transport pipe, wherein the perforated holes are formed in a hydrate enrichment layer in the production well, the natural gas transport pipe has an end disposed in the production well and an end connected to the engineering ship support unit, and a depressurization control valve is disposed on the natural gas transport pipe; the gas isolation and heat insulation unit is regularly laid on a mud volcano, covers the mud volcano and comprises a gas isolation and heat insulation cover connected to the power supply unit, wherein the gas isolation and heat insulation cover sequentially comprises, from bottom to top, a heat-conducting aluminum foil layer, a carbon fiber heating wire layer, an asbestos heat insulation layer and a heat-proof gas isolation layer and supplies heat into a sediment layer to heat a natural gas hydrate reservoir; the gas isolation and heat insulation unit further comprises thermal electrodes which are disposed at positions with a high hydrate saturability and a large thickness, the thermal electrodes and the carbon fiber heating wire layer adopt two independent power supply circuits, and the power supply circuit of the thermal electrodes is separately buried between the asbestos heat insulation layer and the heat-proof gas isolation layer.