The present disclosure belongs to the technical field of new energy utilization, and provides an offshore oscillating water column wave energy conversion device with an external permeable structure. The offshore oscillating water column wave energy conversion device with the external permeable structure comprises an oscillating water column system, an anchoring fixing system and a permeable structure. According to the offshore oscillating water column wave energy conversion device with the external permeable structure provided by the present disclosure, the offshore oscillating water column wave energy conversion device and the permeable structure are effectively combined. Using an offshore floating structure, the offshore oscillating water column wave energy conversion device with the external permeable structure can be applied to deep and far sea areas with higher wave energy density, and the output power of the device can be effectively improved.