The invention relates to an underwater oil storage mat of a production platform, which comprises a mat body, wherein a plurality of oil storage tanks are arranged in the mat body; all the oil storage tanks are communicated through communicating pipes; a plurality of oil inlet pipes and oil outlet pipes and a plurality of water inlet pipes and water outlet pipes are all arranged on the mat body; and an anti-skid device is mounted at the lower part of the mat body. Space arranged in the mat can be utilized for oil storage, so that the demand of the oil storage of the production platform is met and the production cost is saved; furthermore, underwater storage of crude oil can be realized and the safety of the oil storage can be improved. Simultaneously, the mat can be suitable for soft soil foundations, avoid the emergence of hollowing out phenomenon and simultaneously reduce the difficulty in pile insertion and extraction operations.